From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 26 Apr 2005 03:05:17 -0700 From: Andrew Morton Subject: Re: [PATCH]: VM 6/8 page_referenced(): move dirty Message-Id: <20050426030517.0a72ee14.akpm@osdl.org> In-Reply-To: <17006.2975.791376.558683@gargle.gargle.HOWL> References: <16994.40677.105697.817303@gargle.gargle.HOWL> <20050425210016.6f8a47d1.akpm@osdl.org> <17006.127.376459.93584@gargle.gargle.HOWL> <20050426015518.2df35139.akpm@osdl.org> <17006.2975.791376.558683@gargle.gargle.HOWL> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nikita Danilov Cc: linux-mm@kvack.org List-ID: Nikita Danilov wrote: > > Andrew Morton writes: > > Nikita Danilov wrote: > > > > > > > > > > > I can envision workloads (such as mmap 80% of memory and continuously dirty > > > > it) which would end up performing continuous I/O with this patch. > > > > > > Below is a version that tries to move dirtiness to the struct page only > > > if we are really going to deactivate the page. In your scenario above, > > > continuously dirty pages will be on the active list, so it should be > > > okay. > > > > OK, well it'll now increase the amount of I/O by a smaller amount. Trade > > that off against possibly improved I/O patterns. But how do we know that > > all this is a net gain? > > By looking at the (micro-) benchmarking results: > > 2.6.12-rc2: > > before-patch page_referenced-move-dirty > > 45.8 32.3 > 204.3 93.2 > 194.8 89.5 > 194.9 89.9 > 197.7 92.1 > 195.0 90.2 > 199.4 89.5 > 196.3 89.2 hm. What's the reason for such a large difference? That workload should just be doing pretty-much-linear write even if we're writing a page-at-a-time off the tail of the LRU. Was that box SMP? -- 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/ . Don't email: aart@kvack.org