From: Andrea Arcangeli <email@example.com> To: Andrew Morton <firstname.lastname@example.org> Cc: Stephan von Krawczynski <email@example.com>, firstname.lastname@example.org, email@example.com Subject: Re: 2.4.10-pre11: alsaplayer skiping during kernel build (-pre10 did not) Date: Tue, 18 Sep 2001 22:18:54 +0200 [thread overview] Message-ID: <20010918221854.C720@athlon.random> (raw) In-Reply-To: <20010918171416.A6540@planetzork.spacenet> <20010918172500.F19092@athlon.random> <20010918173515.B6698@planetzork.spacenet> <20010918174434.I19092@athlon.random> <20010918175104.D6698@planetzork.spacenet> <firstname.lastname@example.org>, <email@example.com>; <20010918214152.A720@athlon.random> <3BA7A853.4EC44195@zip.com.au> In-Reply-To: <3BA7A853.4EC44195@zip.com.au>; from firstname.lastname@example.org on Tue, Sep 18, 2001 at 01:02:27PM -0700 On Tue, Sep 18, 2001 at 01:02:27PM -0700, Andrew Morton wrote: > Andrea Arcangeli wrote: > > > > I now have an update ready for Linus to merge that should fix the few > > leftovers I had in the very first release of the vm rewrite but of > > course I will be interested to hear about any regression/progression > > about those changes, I'll post them in a few minutes in CC to l-k. > > > > Please include Andi's likely()/unlikely() change - it's nice. I guess I'll postpone the likely/unlikely after resynching with Linus since I'm basically ready to run rsync and I prefer to go sleep early today and to think about new things tomorrow ;). I also have a few arguments about the likely/unlikely to solve before agreeing on it, in particular in all my usages the value will be either 0 or 1 so I don't see why should I tell gcc to do !!, probably it will be optimized away but I also don't see why should the left term matter for an "if", the "if" only cares about zero or non zero, so I should be able to define the fast path with an 1 even if my result is 2, otherwise it sounds like gcc is doing something strange. > I can't measure any obviously new causes of latency in your > VM. It's nice that you've paid attention to this in various > places. thanks. > The main culprits now are the file IO and dirty buffer writeout paths: > up to fifty milliseconds in each. > > I suggest you stick scheduling points in generic_file_read(), > generic_file_write() and write_locked_buffers() and then dispose > of the copy-user-latency patch from -aa kernels. Yes, I pretty much agree on such change, I remeber you just pointed out once. It's postponed to tomorrow too ;). At the moment I just care to post the vm fixes against pre11 plain in order to possibly get some feedback on it while I sleep :) > With the above fixed, the main source of latency is > /proc/meminfo->si_swapinfo(). It's about five milliseconds per gig > of swap, which isn't too bad. But it's directly invokable by > userspace (ie: /usr/bin/top) and really should be made less dumb. ok. Andrea
next prev parent reply other threads:[~2001-09-18 20:18 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2001-09-18 15:14 jogi 2001-09-18 15:25 ` Andrea Arcangeli 2001-09-18 15:35 ` jogi 2001-09-18 15:44 ` Andrea Arcangeli 2001-09-18 15:51 ` jogi 2001-09-18 16:06 ` jogi 2001-09-18 19:28 ` Stephan von Krawczynski 2001-09-18 19:41 ` Andrea Arcangeli 2001-09-18 20:02 ` Andrew Morton 2001-09-18 20:18 ` Andrea Arcangeli [this message] 2001-09-19 12:37 ` Hugh Dickins 2001-09-19 13:21 ` jogi 2001-09-19 14:38 ` jogi 2001-09-18 15:25 ` jogi 2001-09-18 15:31 ` Andrea Arcangeli 2001-09-18 15:43 ` jogi
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