Messages in this thread | | | Date | Fri, 05 Apr 2013 14:31:32 +0800 | From | Simon Jeons <> | Subject | Re: [PATCH] mm: page_alloc: Avoid marking zones full prematurely after zone_reclaim() |
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Hi Michal, On 03/21/2013 04:19 PM, Michal Hocko wrote: > On Thu 21-03-13 10:33:07, Simon Jeons wrote: >> Hi Mel, >> On 03/21/2013 02:19 AM, Mel Gorman wrote: >>> The following problem was reported against a distribution kernel when >>> zone_reclaim was enabled but the same problem applies to the mainline >>> kernel. The reproduction case was as follows >>> >>> 1. Run numactl -m +0 dd if=largefile of=/dev/null >>> This allocates a large number of clean pages in node 0 >> I confuse why this need allocate a large number of clean pages? > It reads from file and puts pages into the page cache. The pages are not > modified so they are clean. Output file is /dev/null so no pages are > written. dd doesn't call fadvise(POSIX_FADV_DONTNEED) on the input file > by default so pages from the file stay in the page cache
I try this in v3.9-rc5: dd if=/dev/sda of=/dev/null bs=1MB 14813+0 records in 14812+0 records out 14812000000 bytes (15 GB) copied, 105.988 s, 140 MB/s
free -m -s 1
total used free shared buffers cached Mem: 7912 1181 6731 0 663 239 -/+ buffers/cache: 277 7634 Swap: 8011 0 8011
It seems that almost 15GB copied before I stop dd, but the used pages which I monitor during dd always around 1200MB. Weird, why?
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