From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from max.fys.ruu.nl (max.fys.ruu.nl [131.211.32.73]) by kvack.org (8.8.7/8.8.7) with ESMTP id UAA16959 for ; Mon, 22 Dec 1997 20:05:03 -0500 Date: Mon, 22 Dec 1997 23:14:33 +0100 (MET) From: Rik van Riel Reply-To: H.H.vanRiel@fys.ruu.nl Subject: Re: mmap-age patch, comments wanted In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Noel Maddy Cc: linux-mm List-ID: On Mon, 22 Dec 1997, Noel Maddy wrote: > That was definitely the case with your older vhand patches -- with > them, I could get about 20M more into virtual memory before > performance started degrading. What I'm seeing now is a change in > performance at the same load level. I'm not sure whether the overall > performance is hurt, because the vanilla kernel thrashes a lot in the > same situation, but the system remains responsive. It could be that > the load takes longer in the vanilla kernel (I'll try to check that > today), but the lack of responsiveness with the mmap-age patch makes > it *seem* slower. With vhand, the kernel didn't properly age user-pages, so swap usage was overly high compared to vanilla or mmap-age, so comparing swap usage is no good indication of system load. Also, between vanilla and mmap-age, the mmap-age patched kernel uses swap more than the vanilla one. But the difference should be very small, so swap usage should still be usable as an indication for VM load. I think that what's really making things slower, is that kswapd now has to scan more pages before it can swap one out. This makes the swapout slower (as MAX_SWAP_FAIL still is set at 3) so there are less free pages left to swap things in again. I'm going to try to resolve this issue right now... Rik. +-----------------------------+------------------------------+ | For Linux mm-patches, go to | "I'm busy managing memory.." | | my homepage (via LinuxHQ). | H.H.vanRiel@fys.ruu.nl | | ...submissions welcome... | http://www.fys.ruu.nl/~riel/ | +-----------------------------+------------------------------+