Messages in this thread | | | Date | Thu, 15 Mar 2007 11:07:45 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH 0/3] VM throttling: avoid blocking occasional writers |
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> On Wed, 14 Mar 2007 21:42:46 +0900 Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com> wrote: > > ... > > > -Solution: > > I consider that all of the dirty pages for the disk have been written > back and that the disk is clean if a process cannot write 'write_chunk' > pages in balance_dirty_pages(). > > To avoid using up the free memory with dirty pages by passing blocking, > this patchset adds a new threshold named vm.dirty_limit_ratio to sysctl. > > It modifies balance_dirty_pages() not to block when the amount of > Dirty+Writeback is less than vm.dirty_limit_ratio percent of the memory. > In the other cases, writers are throttled as current Linux does. > > > In this patchset, vm.dirty_limit_ratio, instead of vm.dirty_ratio, is > used as the clamping level of Dirty+Writeback. And, vm.dirty_ratio is > used as the level at which a writers will itself start writeback of the > dirty pages.
Might be a reasonable solution - let's see what Peter comes up with too.
Comments on the patch:
- Please don't VM_DIRTY_LIMIT_RATIO: just use CTL_UNNUMBERED and leave sysctl.h alone.
- The 40% default is already too high. Let's set this new upper limit to 40% and decrease he non-blocking ratio.
- Please update the procfs documentation in ./Docmentation/
- I wonder if dirty_limit_ratio is the best name we could choose. vm_dirty_blocking_ratio, perhaps? Dunno.
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