From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 11 Jul 2002 15:54:08 -0700 From: William Lee Irwin III Subject: Re: [PATCH] Optimize out pte_chain take three Message-ID: <20020711225408.GH25360@holomorphy.com> References: <20810000.1026311617@baldur.austin.ibm.com> <20020710173254.GS25360@holomorphy.com> <3D2C9288.51BBE4EB@zip.com.au> <20020710222210.GU25360@holomorphy.com> <3D2CD3D3.B43E0E1F@zip.com.au> <20020711015102.GV25360@holomorphy.com> <3D2DE264.17706BB4@zip.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Description: brief message Content-Disposition: inline In-Reply-To: <3D2DE264.17706BB4@zip.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Rik van Riel , Dave McCracken , Linux Memory Management List-ID: On Thu, Jul 11, 2002 at 12:54:12PM -0700, Andrew Morton wrote: > The problem is the access pattern. It shouldn't be random-uniform. > But what should it be? random-gaussian? > So: map a large file, access it random-gaussian. malloc some memory, > access it random-gaussian. Apply eviction pressure. Measure throughput. > Optimise throughput. > Does this not capture what the VM is supposed to do? > What workload is rmap supposed to be good at? I wouldn't go through the trouble of Guassian, a step distribution, i.e. sets A and B with P(A) = p < q = P(B), and "effective detection of the working set" is seeing how much of the working set was retained instead of reclaimed as p -> m(A)/m(A U B) and how much determining it cost in terms of cpu. Or that's my first impression. The distributions P(. | A) and P(. | B) don't matter aside from the probabilities of the whole of A and B themselves and non-uniform creates harder to analyze things as bits of A may well be less likely than bits of B so making P(. | A) and P(. | B) uniform sounds easiest to me. Throughput is probably easy to disturb in unrelated ways, but (of course) necessary to keep track of. Cheers, Bill -- 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/