Messages in this thread | | | Date | Fri, 22 Jul 2005 11:32:52 -0300 | From | Márcio Oliveira <> | Subject | Re: Memory Management |
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Neil Horman wrote:
>On Thu, Jul 21, 2005 at 10:40:54AM -0300, Márcio Oliveira wrote: > > >>>http://people.redhat.com/nhorman/papers/rhel3_vm.pdf >>>I wrote this with norm awhile back. It may help you out. >>>Regards >>>Neil >>> >>> >>> >>> >>Neil, >> >> Thanks.~10-12GB of total RAM (16GB) are >> >> How can Proc virtual memory parameters like inactive_clean_percent, >>overcommit_memory, overcommit_ratio and page_cache help me to solve / >>reduce Out Of Memory conditions on servers with 16GB RAM and lots of GB >>swap? >> >> >> >I wouldn't touch memory overcommit if you are already seeing out of memory >issues. If you are using lots of pagecache, I would suggest increasing >inactive_clean percent, reducing the pagecahce.max value, and modifying the >bdflush parameters in the above document such that bdflush runs sooner, more >often, and does more work per iteration. This will help you move data in >pagecache back to disk more aggressively so that memory will be available for >other purposes, like heap allocations. Also if you're using a Red Hat kernel and >you have 16GB of ram in your system, you're a good candidate for the hugemem >kernel. Rather than a straightforward out of memory condition, you may be >seeing a exhaustion of your kernels address space (check LowFree in >/proc/meminfo). In this even the hugemem kernel will help you in that it >increases your Low Memory address space from 1GB to 4GB, preventing some OOM >conditions. > > > > >> Kernel does not free cached memory (~10-12GB of total RAM - 16GB). Is >>there some way to force the kernel to free cached memory? >> >> >> >Cached memory is freed on demand. Just because its listed under the cached line >below doesn't mean it can't be freed and used for another purpose. Implement >the tunings above, and your situation should improve. > >Regards >Neil > > > >>/proc/meminfo: >> >> total: used: free: shared: buffers: cached: >>Mem: 16603488256 16523333632 80154624 0 70651904 13194563584 >>Swap: 17174257664 11771904 17162485760 >>MemTotal: 16214344 kB >>MemFree: 78276 kB >>Buffers: 68996 kB >>Cached: 12874808 kB >> >>Thanks to all. >> >>Marcio. >> >>
Neil,
Thanks for the answers!
The following lines are the Out Of Memory log:
Jul 20 13:45:44 server kernel: Out of Memory: Killed process 23716 (oracle). Jul 20 13:45:44 server kernel: Fixed up OOM kill of mm-less task Jul 20 13:45:45 server su(pam_unix)[3848]: session closed for user root Jul 20 13:45:48 server kernel: Mem-info: Jul 20 13:45:48 server kernel: Zone:DMA freepages: 1884 min: 0 low: 0 high: 0 Jul 20 13:45:48 server kernel: Zone:Normal freepages: 1084 min: 1279 low: 4544 high: 6304 Jul 20 13:45:48 server kernel: Zone:HighMem freepages:386679 min: 255 low: 61952 high: 92928 Jul 20 13:45:48 server kernel: Free pages: 389647 (386679 HighMem) Jul 20 13:45:48 server kernel: ( Active: 2259787/488777, inactive_laundry: 244282, inactive_clean: 244366, free: 389647 ) Jul 20 13:45:48 server kernel: aa:0 ac:0 id:0 il:0 ic:0 fr:1884 Jul 20 13:45:48 server kernel: aa:1620 ac:1801 id:231 il:15 ic:0 fr:1085 Jul 20 13:45:48 server kernel: aa:1099230 ac:1157136 id:488536 il:244277 ic:244366 fr:386679 Jul 20 13:45:48 server kernel: 0*4kB 0*8kB 1*16kB 1*32kB 1*64kB 0*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 1*4096kB = 7536kB)Jul 20 13:45:48 server kernel: 55*4kB 9*8kB 19*16kB 9*32kB 0*64kB 1*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 0*4096kB = 4340kB) Jul 20 13:45:48 server kernel: 291229*4kB 46179*8kB 711*16kB 1*32kB 1*64kB 1*128kB 1*256kB 1*512kB 0*1024kB 0*2048kB 0*4096kB = 1546716kB) Jul 20 13:45:48 server kernel: Swap cache: add 192990, delete 189665, find 21145/90719, race 0+0 Jul 20 13:45:48 server kernel: 139345 pages of slabcache Jul 20 13:45:48 server kernel: 1890 pages of kernel stacks Jul 20 13:45:48 server kernel: 0 lowmem pagetables, 274854 highmem pagetables Jul 20 13:45:48 server kernel: Free swap: 16749720kB Jul 20 13:45:49 server kernel: 4194304 pages of RAM Jul 20 13:45:49 server kernel: 3899360 pages of HIGHMEM Jul 20 13:45:49 server kernel: 140718 reserved pages Jul 20 13:45:49 server kernel: 35350398 pages shared Jul 20 13:45:49 server kernel: 3325 pages swap cached
/proc/meminfo LowFree info: LowFree: 17068 kB ------> Do you think this value is too low?
Zone:Normal freepages: 1084 min: 1279 low: 4544 high: 6304 ----> (freepages < min) It's normal? Zone:HighMem freepages:386679 min: 255 low: 61952 high: 92928 ----> (freepages < min) It's normal?
Thanks a lot Neil!
Márcio Oliveira.
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