Re: 2.4.8-pre7: still buffer cache problems
From: Rik van Riel <hidden>
Date: 2001-08-09 20:57:03
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On Thu, 9 Aug 2001, marc heckmann wrote:
While 2.4.8-pre7 definitely fixes the "dd if=/dev/zero of=bigfile bs=1000k count=bignumber" case. The "dd if=/dev/hda of=/dev/null" is still quite broken for me.
OK, there is no obvious way to do do drop-behind on buffer cache pages, but I think we can use a quick hack to make the system behave well under the presence of large amounts of buffer cache pages. What we could do is, in refill_inactive_scan(), just moving buffer cache pages to the inactive list regardless of page aging when there are too many buffercache pages around in the system. Does the patch below help you ? regards, Rik -- IA64: a worthy successor to the i860. http://www.surriel.com/ http://www.conectiva.com/ http://distro.conectiva.com/
--- linux-2.4.7-ac7/mm/vmscan.c.buffer Thu Aug 9 17:54:24 2001
+++ linux-2.4.7-ac7/mm/vmscan.c Thu Aug 9 17:55:09 2001@@ -708,6 +708,8 @@ * This function will scan a portion of the active list to find * unused pages, those pages will then be moved to the inactive list. */ +#define too_many_buffers (atomic_read(&buffermem_pages) > \ + (num_physpages * buffer_mem.borrow_percent / 100)) int refill_inactive_scan(zone_t *zone, unsigned int priority, int target) { struct list_head * page_lru;
@@ -770,6 +772,18 @@ page_active = 1; } } + + /* + * If the amount of buffer cache pages is too + * high we just move every buffer cache page we + * find to the inactive list. Eventually they'll + * be reclaimed there... + */ + if (page->buffers && !page->mapping && too_many_buffers) { + deactivate_page_nolock(page); + page_active = 0; + } + /* * If the page is still on the active list, move it * to the other end of the list. Otherwise we exit if --
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