linux – 如何设置shmall,shmmax,shmni等…一般和postgresql

我已经使用 documentation from PostgreSQL来设置它,例如这个配置：

>>> cat /proc/meminfo 
MemTotal:       16345480 kB
MemFree:         1770128 kB
Buffers:          382184 kB
Cached:         10432632 kB
SwapCached:            0 kB
Active:          9228324 kB
Inactive:        4621264 kB
Active(anon):    7019996 kB
Inactive(anon):   548528 kB
Active(file):    2208328 kB
Inactive(file):  4072736 kB
Unevictable:           0 kB
Mlocked:               0 kB
SwapTotal:             0 kB
SwapFree:              0 kB
Dirty:              3432 kB
Writeback:             0 kB
AnonPages:       3034588 kB
Mapped:          4243720 kB
Shmem:           4533752 kB
Slab:             481728 kB
SReclaimable:     440712 kB
SUnreclaim:        41016 kB
KernelStack:        1776 kB
PageTables:        39208 kB
NFS_Unstable:          0 kB
Bounce:                0 kB
WritebackTmp:          0 kB
CommitLimit:     8172740 kB
Committed_AS:   14935216 kB
VmallocTotal:   34359738367 kB
VmallocUsed:      399340 kB
VmallocChunk:   34359334908 kB
HardwareCorrupted:     0 kB
AnonHugePages:    456704 kB
HugePages_Total:       0
HugePages_Free:        0
HugePages_Rsvd:        0
HugePages_Surp:        0
Hugepagesize:       2048 kB
DirectMap4k:       12288 kB
DirectMap2M:    16680960 kB

>>> ipcs -l          

------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 4316816
max total shared memory (kbytes) = 4316816
min seg size (bytes) = 1

------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767

------ Messages Limits --------
max queues system wide = 31918
max size of message (bytes) = 8192
default max size of queue (bytes) = 16384

sysctl.conf提取,由我计算：

kernel.shmall = 1079204
kernel.shmmax = 4420419584

postgresql.conf非默认值,由我计算：

max_connections = 60            # (change requires restart)
shared_buffers = 4GB            # min 128kB
work_mem = 4MB              # min 64kB
wal_sync_method = open_sync     # the default is the first option
checkpoint_segments = 16        # in logfile segments,min 1,16MB each
checkpoint_completion_target = 0.9  # checkpoint target duration,0.0 - 1.0
effective_cache_size = 6GB

这个合适吗？如果不是(或不一定),在哪种情况下是否合适？

我们确实注意到这个配置有很好的性能改进,你会如何改进它？

如何计算内核内存管理参数？

任何人都可以解释如何从头开始真正设置它们吗？

解决方法

Git fails to push with error ‘out of memory’

我不是在这里回答你的所有问题,而是你标题中的问题：

How to set shmall,shmmax,shmni,etc … in general and for postgresql

对于某些内核发行版,有一些设置会阻止内核将最大内存分配给单个进程：

Set Kernel Parameters
Modify the "/etc/sysctl.conf" file to include the lines appropriate to your operating system.
# Red Hat Enterprise Linux 3.0 and CentOS 3.x 
 kernel.shmmax = 2147483648
 kernel.shmmni = 4096
 kernel.shmall = 2097152
 kernel.shmmin = 1
 kernel.shmseg = 10

# semaphores: 
 semmsl,semmns,semopm,semmni kernel.sem = 250 32000 100 128
 fs.file-max = 65536

# Red Hat Enterprise Linux 4.0 and CentOS 4.x 
 kernel.shmmax = 536870912
 kernel.shmmni = 4096
 kernel.shmall = 2097152

如果您的进程超出限制,尽管系统上报告了最大内存,但内核将终止该进程.

注意：请注意这些设置.您可能不希望使用该示例中的设置,因为我从环境中的服务器中提取它们.

一些额外的注意事项：

To Update and test kernel settings with sysctl,use following commands:

List current settings: sysctl -A|grep shm

sysctl -w kernel.shmmax=<value> to write in sysctl.conf
sysctl -p /etc/sysctl.conf to read/reload the values from sysctl.conf

Disable secure linux by editing the "/etc/selinux/config" file,making sure the SELINUX flag is set as follows.

SELINUX=disabled

Is this appropriate ? If not (or not necessarily),in which case would
it be appropriate ?

当ISP提供商不希望单个客户进程占用共享服务器上的所有资源时,通常在数据中心环境中更严格地定义内核设置.

您通常不必设置内核内存参数,除非您有一个由于资源不足而被内核杀死的进程.

在某些情况下,postgres还可以为特定页面大小分配更多内存,而不是共享内存中可用的内容：

* The PostgreSQL server failed to start. Please check the log output:
2011-11-04 05:06:26 UTC FATAL: could not create shared memory segment: Invalid
argument
2011-11-04 05:06:26 UTC DETAIL: Failed system call was shmget(key=5432001,size
=161849344,03600).
2011-11-04 05:06:26 UTC HINT: This error usually means that PostgreSQL’s reques
t for a shared memory segment exceeded your kernel’s SHMMAX parameter. You can
either reduce the request size or reconfigure the kernel with larger SHMMAX. To
reduce the request size (currently 161849344 bytes),reduce PostgreSQL’s shared
_buffers parameter (currently 19200) and/or its max_connections parameter (curre
ntly 53).
If the request size is already small,it’s possible that it is less than
your kernel’s SHMMIN parameter,in which case raising the request size or recon
figuring SHMMIN is called for.
The PostgreSQL documentation contains more information about shared memo
ry configuration.
…fail!

可以通过调整内核资源设置来解决上述示例等错误.此处详细介绍了用于确定资源设置的建议设置和方法：

http://www.postgresql.org/docs/9.1/static/kernel-resources.html

但是,除非遇到与postgres进程相关的资源不足情况,否则您实际上不必触摸这些设置.这些情况通常发生在分配给它们的资源很少的共享环境或服务器中.

Can anybody explain how to really set them from the ground up ?

对于Postgres调整,您应该阅读：

http://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server

（编辑：安卓应用网）

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