xenial (1) memcaslap.1.gz

Provided by: libmemcached-tools_1.0.18-4.1ubuntu2_amd64 bug

NAME

       memaslap - libmemcached Documentation

SYNOPSIS

       memaslap [options]

       --help

       MEMCACHED_SERVERS

DESCRIPTION

       memaslap  is  a  load  generation  and  benchmark  tool  for memcached servers. It generates configurable
       workload such as threads, concurrencies, connections, run time, overwrite, miss  rate,  key  size,  value
       size,  get/set proportion, expected throughput, and so on. Furthermore, it also testss data verification,
       expire-time  verification,  UDP,  binary  protocol,  facebook  test,  replication  test,  multi-get   and
       reconnection, etc.

       Memaslap  manages network connections like memcached with libevent. Each thread of memaslap is bound with
       a CPU core, all the threads don't communicate with each other, and there are several  socket  connections
       in  each  thread.  Each  connection  keeps  key  size  distribution, value size distribution, and command
       distribution by itself.

       You  can  specify  servers  via  the  memslap  --servers  option  or   via   the   environment   variable
       MEMCACHED_SERVERS.

FEATURES

       Memslap is developed to for the following purposes:

       Manages network connections with libevent asynchronously.

       Set both TCP and UDP up to use non-blocking IO.

       Improves parallelism: higher performance in multi-threads environments.

       Improves time efficiency: faster processing speed.

       Generates  key  and  value  more  efficiently;  key  size  distribution  and  value size distribution are
       configurable.

       Supports get, multi-get, and set commands; command distribution is configurable.

       Supports controllable miss rate and overwrite rate.

       Supports data and expire-time verification.

       Supports dumping statistic information periodically.

       Supports thousands of TCP connections.

       Supports binary protocol.

       Supports facebook test (set with TCP and multi-get with UDP) and replication test.

DETAILS

   Effective implementation of network.
       For memaslap, both TCP and UDP use non-blocking network  IO.  All  the  network  events  are  managed  by
       libevent  as  memcached.  The  network  module  of  memaslap is similar to memcached. Libevent can ensure
       memaslap can handle network very efficiently.

   Effective implementation of multi-threads and concurrency
       Memslap has the similar implementation of  multi-threads  to  memcached.  Memslap  creates  one  or  more
       self-governed  threads;  each  thread  is  bound  with one CPU core if the system testss setting CPU core
       affinity.

       In addition, each thread has a libevent to manage the events of the network; each thread has one or  more
       self-governed  concurrencies;  and  each  concurrency  has  one  or  more  socket  connections.  All  the
       concurrencies don’t communicate with each other even though they are in the same thread.

       Memslap can create thousands of socket connections, and each concurrency has tens of socket  connections.
       Each  concurrency  randomly or sequentially selects one socket connection from its socket connection pool
       to run, so memaslap can ensure each concurrency handles one socket connection at any  given  time.  Users
       can  specify  the  number  of  concurrency  and socket connections of each concurrency according to their
       expected workload.

   Effective implementation of generating key and value
       In order to improve time efficiency and space efficiency, memaslap creates a random characters table with
       10M characters. All the suffixes of keys and values are generated from this random characters table.

       Memslap  uses the offset in the character table and the length of the string to identify a string. It can
       save much memory.  Each key contains two parts, a prefix and a suffix.  The  prefix  is  an  uint64_t,  8
       bytes. In order to verify the data set before, memaslap need to ensure each key is unique, so it uses the
       prefix to identify a key. The prefix cannot include illegal characters, such as ‘r’, ‘n’, ‘0’  and  ‘  ‘.
       And memaslap has an algorithm to ensure that.

       Memslap  doesn’t  generate  all  the objects (key-value pairs) at the beginning. It only generates enough
       objects to fill the task window (default 10K objects) of each concurrency. Each object has the  following
       basic  information, key prefix, key suffix offset in the character table, key length, value offset in the
       character table, and value length.

       In the work process, each concurrency sequentially or randomly selects an object from the  window  to  do
       set  operation  or  get operation. At the same time, each concurrency kicks objects out of its window and
       adds new object into it.

   Simple but useful task scheduling
       Memslap uses libevent to schedule all the concurrencies of threads, and each concurrency schedules  tasks
       based on the local task window. Memslap assumes that if each concurrency keeps the same key distribution,
       value distribution and commands distribution, from outside, memaslap keeps  all  the  distribution  as  a
       whole.   Each  task  window  includes a lot of objects, each object stores its basic information, such as
       key, value, expire time, and so on. At any time, all the objects in the window keep the  same  and  fixed
       key and value distribution. If an object is overwritten, the value of the object will be updated. Memslap
       verifies the data or expire-time according to the object information stored in the task window.

       Libevent selects which concurrency to handle based on a specific  network  event.  Then  the  concurrency
       selects  which command (get or set) to operate based on the command distribution. If it needs to kick out
       an old object and add a new object, in order to keep the same key and value distribution, the new  object
       must have the same key length and value length.

       If  memcached  server has two cache layers (memory and SSD), running memaslap with different window sizes
       can get different cache miss rates. If memaslap adds enough objects into the windows  at  the  beginning,
       and  the cache of memcached cannot store all the objects initialized, then memaslap will get some objects
       from the second cache layer. It causes the first cache layer to miss. So the user can specify the  window
       size to get the expected miss rate of the first cache layer.

   Useful implementation of multi-servers , UDP, TCP, multi-get and binary protocol
       Because each thread is self-governed, memaslap can assign different threads to handle different memcached
       servers. This is just one of the ways in which memaslap tests multiple servers. The  only  limitation  is
       that  the  number of servers cannot be greater than the number of threads. The other way to test multiple
       servers is for replication test. Each concurrency has one socket connection  to  each  memcached  server.
       For the implementation, memaslap can set some objects to one memcached server, and get these objects from
       the other servers.

       By default, Memslap does single get. If the user specifies multi-get option, memaslap will collect enough
       get commands and pack and send the commands together.

       Memslap testss both the ASCII protocol and binary protocol, but it runs on the ASCII protocol by default.
       Memslap by default runs on the TCP protocol, but it also tests UDP. Because UDP  is  unreliable,  dropped
       packages  and  out-of-order packages may occur. Memslap creates a memory buffer to handle these problems.
       Memslap tries to read all the response data of one command from the  server  and  reorders  the  response
       data.  If  some  packages  get lost, the waiting timeout mechanism can ensure half-baked packages will be
       discarded and the next command will be sent.

USAGE

       Below are some usage samples:

       memaslap -s 127.0.0.1:11211 -S 5s

       memaslap -s 127.0.0.1:11211 -t 2m -v 0.2 -e 0.05 -b

       memaslap -s 127.0.0.1:11211 -F config -t 2m -w 40k -S 20s -o 0.2

       memaslap -s 127.0.0.1:11211 -F config -t 2m -T 4 -c 128 -d 20 -P 40k

       memaslap -s 127.0.0.1:11211 -F config -t 2m -d 50 -a -n 40

       memaslap -s 127.0.0.1:11211,127.0.0.1:11212 -F config -t 2m

       memaslap -s 127.0.0.1:11211,127.0.0.1:11212 -F config -t 2m -p 2

       The user must specify one server at least to run memaslap.  The  rest  of  the  parameters  have  default
       values, as shown below:

       Thread number = 1                    Concurrency = 16

       Run time = 600 seconds                Configuration file = NULL

       Key size = 64                         Value size = 1024

       Get/set = 9:1                         Window size = 10k

       Execute number = 0                   Single get = true

       Multi-get = false                      Number of sockets of each concurrency = 1

       Reconnect = false                     Data verification = false

       Expire-time verification = false           ASCII protocol = true

       Binary protocol = false                 Dumping statistic information

       periodically = false

       Overwrite proportion = 0%             UDP = false

       TCP = true                           Limit throughput = false

       Facebook test = false                  Replication test = false

   Key size, value size and command distribution.
       All  the  distributions are read from the configuration file specified by user with “—cfg_cmd” option. If
       the user does not specify a configuration file, memaslap will run with the default distribution (key size
       =  64, value size = 1024, get/set = 9:1). For information on how to edit the configuration file, refer to
       the “Configuration File” section.

       The minimum key size is 16 bytes; the maximum key size is 250  bytes.  The  precision  of  proportion  is
       0.001. The proportion of distribution will be rounded to 3 decimal places.

       The  minimum  value  size  is 1 bytes; the maximum value size is 1M bytes. The precision of proportion is
       0.001. The proportion of distribution will be rounded to 3  decimal  places.   Currently,  memaslap  only
       testss  set  and  get  commands.  And  it testss 100% set and 100% get. For 100% get, it will preset some
       objects to the server.

   Multi-thread and concurrency
       The high performance of memaslap benefits from the special  schedule  of  thread  and  concurrency.  It’s
       important to specify the proper number of them. The default number of threads is 1; the default number of
       concurrency is 16. The user can use “—threads” and “--concurrency” to specify these variables.

       If the system tests setting CPU affinity and the number of threads specified by the user is greater  than
       1,  memaslap  will  try  to  bind  each  thread  to  a different CPU core. So if you want to get the best
       performance memaslap, it is better to specify the number of thread equal to the number of CPU cores.  The
       number of threads specified by the user can also be less or greater than the number of CPU cores. Because
       of the limitation of implementation, the number of concurrencies could be the multiple of the  number  of
       threads.

       1. For 8 CPU cores system

       For example:

       --threads=2 --concurrency=128

       --threads=8 --concurrency=128

       --threads=8 --concurrency=256

       --threads=12 --concurrency=144

       2. For 16 CPU cores system

       For example:

       --threads=8 --concurrency=128

       --threads=16 --concurrency=256

       --threads=16 --concurrency=512

       --threads=24 --concurrency=288

       The  memaslap  performs  very  well, when used to test the performance of memcached servers.  Most of the
       time, the bottleneck is the network or the server. If for  some  reason  the  user  wants  to  limit  the
       performance of memaslap, there are two ways to do this:

       Decrease the number of threads and concurrencies.  Use the option “--tps” that memaslap provides to limit
       the throughput. This option allows the user to get the expected throughput. For example, assume that  the
       maximum  throughput is 50 kops/s for a specific configuration, you can specify the throughput equal to or
       less than the maximum throughput using “--tps” option.

   Window size
       Most of the time, the user does not need to specify the window size. The default window size is 10k.  For
       Schooner  Memcached,  the user can specify different window sizes to get different cache miss rates based
       on the test case. Memslap testss cache miss rate between 0% and 100%.  If you use this  utility  to  test
       the  performance  of  Schooner  Memcached, you can specify a proper window size to get the expected cache
       miss rate. The formula for calculating window size is as follows:

       Assume that the key size is 128 bytes, and the value size is 2048 bytes, and concurrency=128.

       1. Small cache cache_size=1M, 100% cache miss (all data get from SSD).  win_size=10k

       2. cache_size=4G

       (1). cache miss rate 0%

       win_size=8k

       (2). cache miss rate 5%

       win_size=11k

       3. cache_size=16G

       (1). cache miss rate 0%

       win_size=32k

       (2). cache miss

       rate 5%

       win_size=46k

       The formula for calculating window size for cache miss rate 0%:

       cache_size / concurrency / (key_size + value_size) * 0.5

       The formula for calculating window size for cache miss rate 5%:

       cache_size / concurrency / (key_size + value_size) * 0.7

   Verification
       Memslap testss both data verification and expire-time verification. The user can use "--verify=" or  "-v"
       to specify the proportion of data verification. In theory, it testss 100% data verification. The user can
       use "--exp_verify=" or "-e" to specify the proportion of expire-time verification. In theory,  it  testss
       100% expire-time verification. Specify the "--verbose" options to get more detailed error information.

       For example: --exp_verify=0.01 –verify=0.1 , it means that 1% of the objects set with expire-time, 10% of
       the objects gotten will be verified. If the objects are gotten, memaslap will verify the expire-time  and
       value.

   multi-servers and multi-config
       Memslap  testss  multi-servers  based  on self-governed thread.  There is a limitation that the number of
       servers cannot be greater than the number of threads. Memslap assigns one thread to handle one server  at
       least. The user can use the "--servers=" or "-s" option to specify multi-servers.

       For example:

       --servers=10.1.1.1:11211,10.1.1.2:11212,10.1.1.3:11213 --threads=6 --concurrency=36

       The  above  command  means  that  there  are  6 threads, with each thread having 6 concurrencies and that
       threads 0 and 3 handle server 0 (10.1.1.1); threads 1 and 4 handle server 1 (10.1.1.2); and thread 2  and
       5 handle server 2 (10.1.1.3).

       All the threads and concurrencies in memaslap are self-governed.

       So  is memaslap. The user can start up several memaslap instances. The user can run memaslap on different
       client machines to communicate with the same memcached server at the same. It  is  recommended  that  the
       user start different memaslap on different machines using the same configuration.

   Run with execute number mode or time mode
       The  default  memaslap runs with time mode. The default run time is 10 minutes. If it times out, memaslap
       will exit. Do not specify both execute number mode and time mode at  the  same  time;  just  specify  one
       instead.

       For example:

       --time=30s (It means the test will run 30 seconds.)

       --execute_number=100000 (It means that after running 100000 commands, the test will exit.)

   Dump statistic information periodically.
       The user can use "--stat_freq=" or "-S" to specify the frequency.

       For example:

       --stat_freq=20s

       Memslap will dump the statistics of the commands (get and set) at the frequency of every 20 seconds.

       For more information on the format of dumping statistic information, refer to “Format of Output” section.

   Multi-get
       The  user  can use "--division=" or "-d" to specify multi-get keys count.  Memslap by default does single
       get with TCP. Memslap also testss data verification and expire-time verification for multi-get.

       Memslap testss multi-get with both TCP and UDP. Because of the  different  implementation  of  the  ASCII
       protocol  and  binary  protocol,  there  are  some  differences  between the two. For the ASCII protocol,
       memaslap sends one “multi-get” to the server once. For the binary protocol, memaslap sends several single
       get commands together as “multi-get” to the server.

   UDP and TCP
       Memslap  testss  both  UDP  and  TCP. For TCP, memaslap does not reconnect the memcached server if socket
       connections are lost. If all the socket connections are lost or memcached server crashes,  memaslap  will
       exit.  If the user specifies the “--reconnect” option when socket connections are lost, it will reconnect
       them.

       User can use “--udp” to enable the UDP feature, but UDP comes with some limitations:

       UDP cannot set data more than 1400 bytes.

       UDP is not testsed by the binary protocol because the binary protocol of memcached does not tests that.

       UDP doesn’t tests reconnection.

   Facebook test
       Set data with TCP and multi-get with UDP. Specify the following options:

       "--facebook --division=50"

       If you want to create thousands of TCP connections, specify the

       "--conn_sock=" option.

       For example: --facebook --division=50 --conn_sock=200

       The above command means that memaslap will  do  facebook  test,  each  concurrency  has  200  socket  TCP
       connections and one UDP socket.

       Memslap sets objects with the TCP socket, and multi-gets 50 objects once with the UDP socket.

       If  you  specify  "--division=50", the key size must be less that 25 bytes because the UDP packet size is
       1400 bytes.

   Replication test
       For replication test, the  user  must  specify  at  least  two  memcached  servers.   The  user  can  use
       “—rep_write=” option to enable feature.

       For example:

       --servers=10.1.1.1:11211,10.1.1.2:11212 –rep_write=2

       The above command means that there are 2 replication memcached servers, memaslap will set objects to both
       server 0 and server 1, get objects which are set to server 0 before from server 1, and also  get  objects
       which  are set to server 1 before from server 0. If server 0 crashes, memaslap will only get objects from
       server 1. If server 0 comes back to life again, memaslap will reconnect server 0. If both  server  0  and
       server 1 crash, memaslap will exit.

   Supports thousands of TCP connections
       Start  memaslap  with "--conn_sock=" or "-n" to enable this feature. Make sure that your system can tests
       opening thousands of files and creating thousands of  sockets.  However,  this  feature  does  not  tests
       reconnection if sockets disconnect.

       For example:

       --threads=8 --concurrency=128 --conn_sock=128

       The  above  command  means  that  memaslap  starts  up  8 threads, each thread has 16 concurrencies, each
       concurrency has 128 TCP socket connections, and the total number of TCP socket connections is 128 * 128 =
       16384.

   Supports binary protocol
       Start  memaslap  with "--binary" or "-B" options to enable this feature. It testss all the above features
       except UDP, because the latest memcached 1.3.3 does not implement binary UDP protocol.

       For example:

       --binary

       Since memcached 1.3.3 doesn't implement binary UDP protocol, memaslap does not tests  UDP.  In  addition,
       memcached  1.3.3  does  not  tests multi-get. If you specify "--division=50" option, it just sends 50 get
       commands together as “mulit-get” to the server.

CONFIGURATION FILE

       This section describes the format of the configuration file.  By default when no  configuration  file  is
       specified memaslap reads the default one located at ~/.memaslap.cnf.

       Below is a sample configuration file:

          ---------------------------------------------------------------------------
          #comments should start with '#'
          #key
          #start_len end_len proportion
          #
          #key length range from start_len to end_len
          #start_len must be equal to or greater than 16
          #end_len must be equal to or less than 250
          #start_len must be equal to or greater than end_len
          #memaslap will generate keys according to the key range
          #proportion: indicates keys generated from one range accounts for the total
          generated keys
          #
          #example1: key range 16~100 accounts for 80%
          #          key range 101~200 accounts for 10%
          #          key range 201~250 accounts for 10%
          #          total should be 1 (0.8+0.1+0.1 = 1)
          #
          #          16 100 0.8
          #          101 200 0.1
          #          201 249 0.1
          #
          #example2: all keys length are 128 bytes
          #
          #          128 128 1
          key
          128 128 1
          #value
          #start_len end_len proportion
          #
          #value length range from start_len to end_len
          #start_len must be equal to or greater than 1
          #end_len must be equal to or less than 1M
          #start_len must be equal to or greater than end_len
          #memaslap will generate values according to the value range
          #proportion: indicates values generated from one range accounts for the
          total generated values
          #
          #example1: value range 1~1000 accounts for 80%
          #          value range 1001~10000 accounts for 10%
          #          value range 10001~100000 accounts for 10%
          #          total should be 1 (0.8+0.1+0.1 = 1)
          #
          #          1 1000 0.8
          #          1001 10000 0.1
          #          10001 100000 0.1
          #
          #example2: all value length are 128 bytes
          #
          #          128 128 1
          value
          2048 2048 1
          #cmd
          #cmd_type cmd_proportion
          #
          #currently memaslap only testss get and set command.
          #
          #cmd_type
          #set     0
          #get     1
          #
          #example: set command accounts for 50%
          #         get command accounts for 50%
          #         total should be 1 (0.5+0.5 = 1)
          #
          #         cmd
          #         0    0.5
          #         1    0.5
          cmd
          0    0.1
          1.0 0.9

FORMAT OF OUTPUT

       At the beginning, memaslap displays some configuration information as follows:

       servers : 127.0.0.1:11211

       threads count: 1

       concurrency: 16

       run time: 20s

       windows size: 10k

       set proportion: set_prop=0.10

       get proportion: get_prop=0.90

   Where
       servers : "servers"
          The servers used by memaslap.

       threads count
          The number of threads memaslap runs with.

       concurrency
          The number of concurrencies memaslap runs with.

       run time
          How long to run memaslap.

       windows size
          The task window size of each concurrency.

       set proportion
          The proportion of set command.

       get proportion
          The proportion of get command.

       The output of dynamic statistics is something like this:

          ---------------------------------------------------------------------------------------------------------------------------------
          Get Statistics
          Type  Time(s)  Ops   TPS(ops/s)  Net(M/s)  Get_miss  Min(us)  Max(us)
          Avg(us)  Std_dev    Geo_dist
          Period   5   345826  69165     65.3      0         27      2198     203
          95.43      177.29
          Global  20  1257935  62896     71.8      0         26      3791     224
          117.79     192.60

          Set Statistics
          Type  Time(s)  Ops   TPS(ops/s)  Net(M/s)  Get_miss  Min(us)  Max(us)
          Avg(us)  Std_dev    Geo_dist
          Period   5    38425   7685      7.3       0         42      628     240
          88.05      220.21
          Global   20   139780  6989      8.0       0         37      3790    253
          117.93     224.83

          Total Statistics
          Type  Time(s)  Ops   TPS(ops/s)  Net(M/s)  Get_miss  Min(us)  Max(us)
          Avg(us)  Std_dev    Geo_dist
          Period   5   384252   76850     72.5      0        27      2198     207
          94.72      181.18
          Global  20  1397720   69886     79.7      0        26      3791     227
          117.93     195.60
          ---------------------------------------------------------------------------------------------------------------------------------

   Where
       Get Statistics
          Statistics information of get command

       Set Statistics
          Statistics information of set command

       Total Statistics
          Statistics information of both get and set command

       Period
          Result within a period

       Global
          Accumulated results

       Ops
          Total operations

       TPS
          Throughput, operations/second

       Net
          The rate of network

       Get_miss
          How many objects can’t be gotten

       Min
          The minimum response time

       Max
          The maximum response time

       Avg:
          The average response time

       Std_dev
          Standard deviation of response time

       Geo_dist
          Geometric distribution based on natural exponential function

       At the end, memaslap will output something like this:

          ---------------------------------------------------------------------------------------------------------------------------------
          Get Statistics (1257956 events)
            Min:        26
            Max:      3791
            Avg:       224
            Geo:    192.60
            Std:    116.23
                            Log2 Dist:
                              4:        0       10    84490   215345
                              8:   484890   459823    12543      824
                             12:       31

           Set Statistics (139782 events)
              Min:        37
              Max:      3790
              Avg:       253
              Geo:    224.84
              Std:    116.83
              Log2 Dist:
                4:        0        0     4200 16988
                8:    50784    65574 2064      167
                12:        5

            Total Statistics (1397738 events)
                Min:        26
                Max:      3791
                Avg:       227
                Geo:    195.60
                Std:    116.60
                Log2 Dist:
                  4:        0       10    88690   232333
                  8:   535674   525397    14607      991
                  12:       36

          cmd_get: 1257969
          cmd_set: 139785
          get_misses: 0
          verify_misses: 0
          verify_failed: 0
          expired_get: 0
          unexpired_unget: 0
          written_bytes: 242516030
          read_bytes: 1003702556
          object_bytes: 152086080
          packet_disorder: 0
          packet_drop: 0
          udp_timeout: 0

          Run time: 20.0s Ops: 1397754 TPS: 69817 Net_rate: 59.4M/s
          ---------------------------------------------------------------------------------------------------------------------------------

   Where
       Get Statistics
          Get statistics of response time

       Set Statistics
          Set statistics of response time

       Total Statistics
          Both get and set statistics of response time

       Min
          The accumulated and minimum response time

       Max
          The accumulated and maximum response time

       Avg
          The accumulated and average response time

       Std
          Standard deviation of response time

       Log2 Dist
          Geometric distribution based on logarithm 2

       cmd_get
          Total get commands done

       cmd_set
          Total set commands done

       get_misses
          How many objects can’t be gotten from server

       verify_misses
          How many objects need to verify but can’t get them

       verify_failed
          How many objects with insistent value

       expired_get
          How many objects are expired but we get them

       unexpired_unget
          How many objects are unexpired but we can’t get them

       written_bytes
          Total written bytes

       read_bytes
          Total read bytes

       object_bytes
          Total object bytes

       packet_disorder
          How many UDP packages are disorder

       packet_drop
          How many UDP packages are lost

       udp_timeout
          How many times UDP time out happen

       Run time
          Total run time

       Ops
          Total operations

       TPS
          Throughput, operations/second

       Net_rate
          The average rate of network

OPTIONS

       -s, --servers=
              List  one  or  more  servers  to  connect.  Servers  count  must be less than threads count. e.g.:
              --servers=localhost:1234,localhost:11211

       -T, --threads=
              Number of threads to startup, better equal to CPU numbers. Default 8.

       -c, --concurrency=
              Number of concurrency to simulate with load. Default 128.

       -n, --conn_sock=
              Number of TCP socks per concurrency. Default 1.

       -x, --execute_number=
              Number of operations(get and set) to execute for the given test. Default 1000000.

       -t, --time=
              How long the test to run, suffix: s-seconds, m-minutes, h-hours, d-days e.g.: --time=2h.

       -F, --cfg_cmd=
              Load the configure file to get command,key and value distribution list.

       -w, --win_size=
              Task window size of each concurrency, suffix: K, M e.g.: --win_size=10k.  Default 10k.

       -X, --fixed_size=
              Fixed length of value.

       -v, --verify=
              The proportion of date verification, e.g.: --verify=0.01

       -d, --division=
              Number of keys to multi-get once. Default 1, means single get.

       -S, --stat_freq=
              Frequency of dumping statistic information. suffix: s-seconds, m-minutes, e.g.: --resp_freq=10s.

       -e, --exp_verify=
              The proportion of objects with expire time,  e.g.:  --exp_verify=0.01.   Default  no  object  with
              expire time

       -o, --overwrite=
              The proportion of objects need overwrite, e.g.: --overwrite=0.01.  Default never overwrite object.

       -R, --reconnect
              Reconnect tests, when connection is closed it will be reconnected.

       -U, --udp
              UDP tests, default memaslap uses TCP, TCP port and UDP port of server must be same.

       -a, --facebook
              Whether it enables facebook test feature, set with TCP and multi-get with UDP.

       -B, --binary
              Whether it enables binary protocol. Default with ASCII protocol.

       -P, --tps=
              Expected throughput, suffix: K, e.g.: --tps=10k.

       -p, --rep_write=
              The first nth servers can write data, e.g.: --rep_write=2.

       -b, --verbose
              Whether it outputs detailed information when verification fails.

       -h, --help
              Display this message and then exit.

       -V, --version
              Display the version of the application and then exit.

EXAMPLES

       memaslap -s 127.0.0.1:11211 -S 5s

       memaslap -s 127.0.0.1:11211 -t 2m -v 0.2 -e 0.05 -b

       memaslap -s 127.0.0.1:11211 -F config -t 2m -w 40k -S 20s -o 0.2

       memaslap -s 127.0.0.1:11211 -F config -t 2m -T 4 -c 128 -d 20 -P 40k

       memaslap -s 127.0.0.1:11211 -F config -t 2m -d 50 -a -n 40

       memaslap -s 127.0.0.1:11211,127.0.0.1:11212 -F config -t 2m

       memaslap -s 127.0.0.1:11211,127.0.0.1:11212 -F config -t 2m -p 2

HOME

       To find out more information please check: http://libmemcached.org/

AUTHORS

       Mingqiang Zhuang <mingqiangzhuang@hengtiansoft.com> (Schooner Technolgy) Brian Aker, <brian@tangent.org>

SEE ALSO

       memcached(1) libmemcached(3)

AUTHOR

       Brian Aker

       2011-2013, Brian Aker DataDifferential, http://datadifferential.com/