grep KSM /boot/config-3.2.0-23-generic CONFIG_KSM=y cat /sys/kernel/mm/ksm/pages_shared 0 cat /sys/kernel/mm/ksm/pages_sharing 0 cat /sys/kernel/mm/ksm/pages_unshared 0
内核：3.2.0-23泛型
Ubuntu 12.04 LTS 64位桌面
免费-m
total used free shared buffers cached Mem: 1964 1883 81 0 11 228 -/+ buffers/cache: 1644 320 Swap: 2008 485 1523
ipcs -m
------ Shared Memory Segments -------- key shmid owner perms bytes nattch status 0x00000000 0 myexperiments 600 393216 2 dest 0x00000000 2490369 myexperiments 600 393216 2 dest 0x00000000 98306 myexperiments 600 393216 2 dest 0x00000000 2523139 myexperiments 600 393216 2 dest 0x00000000 13008900 myexperiments 666 262080 1 dest 0x00000000 1245189 myexperiments 666 4 2 dest 0x00000000 1277958 myexperiments 666 4 1 dest 0x00000000 6520839 myexperiments 600 393216 2 dest 0x00000000 14811144 myexperiments 666 1277760 3 dest 0x00000000 12648458 myexperiments 666 300000 1 dest 0x00000000 8060939 myexperiments 666 300000 1 dest 0x00000000 12943373 myexperiments 666 300000 2 dest 0x00000000 12976142 myexperiments 666 262080 2 dest 0x00000000 13271055 myexperiments 666 300000 2 dest
解决方法
MADV_MERGEABLE (since Linux 2.6.32):
Enable Kernel Samepage Merging (KSM) for the pages in the range specified by addr and length. The kernel regularly scans those areas of user memory that have been marked as mergeable,looking for pages with identical content. These are replaced by a single write-protected page (which is automatically copied if a process later wants to update the content of the page). KSM only merges private anonymous pages (see mmap(2)).
The KSM feature is intended for applications that generate many instances of the same data (e.g.,virtualization systems such as KVM). It can consume a lot of processing power; use with care. See the kernel source file Documentation/vm/ksm.txt for more details. The MADV_MERGEABLE and MADV_UNMERGEABLE operations are only available if the kernel was configured with CONFIG_KSM.