From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from atlas.CARNet.hr (zcalusic@atlas.CARNet.hr [161.53.123.163]) by kvack.org (8.8.7/8.8.7) with ESMTP id RAA18967 for ; Wed, 18 Nov 1998 17:51:13 -0500 Subject: Re: unexpected paging during large file reads in 2.1.127 References: <199811161959.TAA07259@dax.scot.redhat.com> <199811162305.XAA07996@dax.scot.redhat.com> <87lnlb5d2t.fsf@atlas.CARNet.hr> <199811171200.MAA01162@dax.scot.redhat.com> Reply-To: Zlatko.Calusic@CARNet.hr From: Zlatko Calusic Date: 18 Nov 1998 23:50:07 +0100 In-Reply-To: "Stephen C. Tweedie"'s message of "Tue, 17 Nov 1998 12:00:37 GMT" Message-ID: <87d86kwr8g.fsf@atlas.CARNet.hr> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org To: "Stephen C. Tweedie" Cc: Linux-MM List , Linux Kernel List , Rik van Riel , "David J. Fred" List-ID: "Stephen C. Tweedie" writes: > Hi, > > On 17 Nov 1998 02:21:14 +0100, Zlatko Calusic > said: > > > "Stephen C. Tweedie" writes: > > >> No, we don't. We don't evict just-read-in data, because we mark such > >> pages as PG_Referenced. It takes two complete shrink_mmap() passes > >> before we can evict such pages. > > > I didn't find this in the source (in fact, add_to_page_cache clears > > PG_referenced bit, if I understood source correctly). But, see below. > > You didn't understand the source correctly. :) There is an extra > bracket you missed: > > page->flags = (page->flags & ~((1 << PG_uptodate) | (1 << PG_error))) | (1 << PG_referenced); > > We clear PG_uptodate and PG_error, but we _set_ PG_referenced. Oops. My apologies. You're right, of course. That makes one line in my patch superfluous. Although I have some experience in LISP, it looks like I still have trouble counting parentheses (LISP = Lost In Stupid Parentheses). :) Still, a small comment above that line would be extremely helpful. > > > I must agree entirely, because with small patch you can find below, > > performance is very very good. Thanks to marking readahead pages as > > referenced, I've been able to see exact behaviour that I wanted for a > > long time. > > Excellent. > Pleasure is all mine. :) I mean, bits from the patch are coming exclusively from you. I'm really looking forward to their integration in the mainstream, because performance improvement is so dramatic that I expect lots of comments on the linux-kernel list telling that "latest 2.1.xxx is so much faster". Thanks for your good work! -- Posted by Zlatko Calusic E-mail: --------------------------------------------------------------------- "Luke... Luke... Use the MOUSE, Luke" - Obi Wan Gates -- This is a majordomo managed list. To unsubscribe, send a message with the body 'unsubscribe linux-mm me@address' to: majordomo@kvack.org