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I'm using Ubuntu with kernel 3.2.1, x86_64. I'm trying to benchmark a file system, and I want to limit the page cache size to avoid the file system cache taking up too much RAM, which would obviously improve performance (but would not reflect the results on systems with less memory).

Is there a way to do that? I've seen an option in some RHEL distribution for tuning /proc/sys/vm/pagecaches which seems to satisfy this, but I dont see anything useful in Ubuntu except dirty_background_ratio, which will only trigger flushing to disk, not more caching (so I can get a lot more sync I/O etc)

Thank you

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1 回答 1

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ubuntu 似乎没有 vm.pagecache 设置

ls -l /proc/sys/vm/
total 0
-rw-r--r-- 1 root root 0 Jun 17 14:13 block_dump
--w------- 1 root root 0 Jun 17 14:13 compact_memory
-rw-r--r-- 1 root root 0 Jun 17 14:13 dirty_background_bytes
-rw-r--r-- 1 root root 0 Jun 17 09:16 dirty_background_ratio
-rw-r--r-- 1 root root 0 Jun 17 14:13 dirty_bytes
-rw-r--r-- 1 root root 0 Jun 17 14:13 dirty_expire_centisecs
-rw-r--r-- 1 root root 0 Jun 17 09:16 dirty_ratio
-rw-r--r-- 1 root root 0 Jun 17 09:16 dirty_writeback_centisecs
-rw-r--r-- 1 root root 0 Jun 17 14:13 drop_caches
-rw-r--r-- 1 root root 0 Jun 17 14:13 extfrag_threshold
-rw-r--r-- 1 root root 0 Jun 17 14:13 hugepages_treat_as_movable
-rw-r--r-- 1 root root 0 Jun 17 14:13 hugetlb_shm_group
-rw-r--r-- 1 root root 0 Jun 17 09:16 laptop_mode
-rw-r--r-- 1 root root 0 Jun 17 14:13 legacy_va_layout
-rw-r--r-- 1 root root 0 Jun 17 14:13 lowmem_reserve_ratio
-rw-r--r-- 1 root root 0 Jun 17 14:13 max_map_count
-rw-r--r-- 1 root root 0 Jun 17 14:13 memory_failure_early_kill
-rw-r--r-- 1 root root 0 Jun 17 14:13 memory_failure_recovery
-rw-r--r-- 1 root root 0 Jun 17 14:13 min_free_kbytes
-rw-r--r-- 1 root root 0 Jun 17 14:13 min_slab_ratio
-rw-r--r-- 1 root root 0 Jun 17 14:13 min_unmapped_ratio
-rw-r--r-- 1 root root 0 Jun 17 09:15 mmap_min_addr
-rw-r--r-- 1 root root 0 Jun 17 14:13 nr_hugepages
-rw-r--r-- 1 root root 0 Jun 17 14:13 nr_hugepages_mempolicy
-rw-r--r-- 1 root root 0 Jun 17 14:13 nr_overcommit_hugepages
-r--r--r-- 1 root root 0 Jun 17 14:13 nr_pdflush_threads
-rw-r--r-- 1 root root 0 Jun 17 14:13 numa_zonelist_order
-rw-r--r-- 1 root root 0 Jun 17 14:13 oom_dump_tasks
-rw-r--r-- 1 root root 0 Jun 17 14:13 oom_kill_allocating_task
-rw-r--r-- 1 root root 0 Jun 17 09:15 overcommit_memory
-rw-r--r-- 1 root root 0 Jun 17 14:13 overcommit_ratio
-rw-r--r-- 1 root root 0 Jun 17 14:13 page-cluster
-rw-r--r-- 1 root root 0 Jun 17 14:13 panic_on_oom
-rw-r--r-- 1 root root 0 Jun 17 14:13 percpu_pagelist_fraction
-rw-r--r-- 1 root root 0 Jun 17 14:13 scan_unevictable_pages
-rw-r--r-- 1 root root 0 Jun 17 14:13 stat_interval
-rw-r--r-- 1 root root 0 Jun 17 14:13 swappiness
-rw-r--r-- 1 root root 0 Jun 17 14:13 vfs_cache_pressure
-rw-r--r-- 1 root root 0 Jun 17 14:13 zone_reclaim_mode

您可以尝试以下方法：

vi /etc/sysctl.conf

vm.min_free_kbytes=1024
vm.swappiness = 100

然后运行

sysctl -p
vm.min_free_kbytes = 1024
vm.swappiness = 100

不确定它是否有任何帮助。

swapiness 100 内存耗尽时将更多应用程序数据交换到磁盘

于 2013-06-17T13:21:23.507 回答