From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 8 Mar 2001 19:47:59 -0300 (BRT) From: Marcelo Tosatti Subject: Re: nr_async_pages and swapin readahead on -ac series In-Reply-To: <20010308201714.O10437@redhat.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: "Stephen C. Tweedie" Cc: Rik van Riel , linux-mm@kvack.org, Alan Cox List-ID: On Thu, 8 Mar 2001, Stephen C. Tweedie wrote: > Hi, > > On Wed, Mar 07, 2001 at 10:57:21PM -0300, Marcelo Tosatti wrote: > > > > On the latest 2.4 -ac series, nr_async_pages is only being used to count > > swap outs, and not for both swap reads and writes (as Linus tree does). > > Seems fine to me. > > > The problem is that nr_async_pages is used to limit swapin readahead based > > on the number of on flight swap pages (mm/memory.c::swapin_readahead): > > That's probably a mistake: we don't throttle readahead on normal files > in this manner. > > Swapin is always synchronous: it happens in response to a task's page > fault. As such it is always going to be rate-limited automatically. > I don't think it's too important to count reads in nr_async_pages, nor > to throttle readaheads if nr_async_pages is too large. Its not really throttling. We just _bypass_ the readahead's in case we got too much. -- 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.eu.org/Linux-MM/