Messages in this thread | | | Date | Fri, 11 May 2001 13:42:57 -0300 (BRT) | From | Marcelo Tosatti <> | Subject | Re: [PATCH] VM fixes against 2.4.4-ac6 |
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On Fri, 11 May 2001, Marcelo Tosatti wrote:
> Hi, > > The following patch addresses two issues: > > > - Buffer cache pages in the inactive lists are not getting their age > increased if they get touched by getblk (which will set the referenced bit > on the page). page_launder() simply cleans the referenced bit on such > pages and moves them to the active list. To resume: buffercache pages > suffer more pressure from VM than pagecache pages. That is horrible for > performance. > > > - When there is no memory available on the system for normal allocations > (GFP_KERNEL), the tasks may loop in try_to_free_pages() (which is here > called by __alloc_pages()) without blocking: > > - GFP_BUFFER allocations will _never_ block on IO inside > try_to_free_pages(). They will keep looping inside __alloc_pages() > until they get a free page. > > - __GFP_IO|__GFP_WAIT allocations may not find any way to block on > IO inside try_to_free_pages() in case we already have other tasks > inside there (kswapd will be there in such condition, for sure).
Ah, one subtle issue here: if they loop, they'll probably bump memory_pressure a lot.
That will result in a bigger inactive target, which means aggressive aging.
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