From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from digeo-nav01.digeo.com (digeo-nav01.digeo.com [192.168.1.233]) by packet.digeo.com (8.9.3+Sun/8.9.3) with SMTP id LAA28234 for ; Sun, 15 Sep 2002 11:39:26 -0700 (PDT) Message-ID: <3D84D799.557653C7@digeo.com> Date: Sun, 15 Sep 2002 11:55:21 -0700 From: Andrew Morton MIME-Version: 1.0 Subject: Re: 2.5.34-mm4 References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: "M. Edward Borasky" , Axel Siebenwirth , Con Kolivas , lkml , linux-mm@kvack.org, lse-tech@lists.sourceforge.net List-ID: Rik van Riel wrote: > > On Sun, 15 Sep 2002, M. Edward Borasky wrote: > > > Borasky's Corollary 1: If you *can* measure it and it *does* exist, the > > cheapest solution may still be to buy more memory, more disks or a > > faster processor. > > Current 2.5 is sluggish on systems with a fast CPU and 768 MB > of RAM, whereas current -ac runs the same workload smoothly > with 128 MB of RAM. > I've been running 2.5 on my desktop at work (800MHz/256M UP) since 2.5.26 and on the machine at home (Dual 850MHz/768M) on-and-off (recent freizures sent that machine back to Marcelo; need to try again). I also ran 2.4.19-ac-something for a couple of weeks. Impressions are: - 2.5 swaps a lot in response to heavy pagecache activity. SEGQ didn't change that, actually. And this is correct, as-designed behaviour. We'll need some "don't be irritating" knob to prevent this. Or speculative pagein when the load has subsided, which would be a fair-sized project. - In both -ac and 2.5 the scheduler is prone to starving interactive applications (netscape 4, gkrellm, command-line gdb, others) when there is a compilation happening. This is very, very noticeable; and it afects applications which do not use sched_yield(). Ingo has put some extra stuff in since then and I need to retest. - In -ac, there are noticeable stalls during heavy writeout. This may be an ext3 thing, but I can't think of any IO scheduling differences in -ac ext3. I'd be guessing that it is due to bdflush/kupdate lumpiness. Overall I find Marcelo kernels to be the most comfortable, followed by 2.5. Alan's kernels I find to be the least comfortable in a "developer's desktop" situation. -- 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/