From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from burns.conectiva (burns.conectiva [10.0.0.4]) by perninha.conectiva.com.br (Postfix) with SMTP id 9C18838D29 for ; Thu, 9 Aug 2001 17:56:00 -0300 (EST) Date: Thu, 9 Aug 2001 17:55:59 -0300 (BRST) From: Rik van Riel Subject: Re: 2.4.8-pre7: still buffer cache problems In-Reply-To: <32774.213.7.60.90.997365391.squirrel@webmail.hbesoftware.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: marc heckmann Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/