From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dax.scot.redhat.com (sct@dax.scot.redhat.com [195.89.149.242]) by kvack.org (8.8.7/8.8.7) with ESMTP id LAA08614 for ; Tue, 12 Jan 1999 11:11:10 -0500 Date: Tue, 12 Jan 1999 16:10:42 GMT Message-Id: <199901121610.QAA04831@dax.scot.redhat.com> From: "Stephen C. Tweedie" MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: Re: question about try_to_swap_out() In-Reply-To: <199901110338.VAA19737@feta.cs.utexas.edu> References: <199901110338.VAA19737@feta.cs.utexas.edu> Sender: owner-linux-mm@kvack.org To: "Paul R. Wilson" Cc: linux-mm@kvack.org, Stephen Tweedie List-ID: Hi, On Sun, 10 Jan 1999 21:38:46 -0600, "Paul R. Wilson" said: > After checking that that a page is present and pageable, try_to_swap_out() > checks to see if the page is reserved or locked or not DMA'able when > where looking for a DMA page. If any of these three things is > true, it returns 0 without changing anything. > It seems to me that it should go ahead and check the pte age bit, > and update the page frame's PG_referenced bit, before returning 0. Not really. Reserved pages never get swapped anyway. For DMA, we don't want to disturb non-DMA processes at all --- the demand for DMA and non-DMA pages might be very different. For locked pages, we expect this to be sufficiently rare that it's totally irrelevant whether we age the page or not. > Am I off-base here, or should the conditional that checks to see > whether a page is young (and updates the reference bits) be moved > up ahead of the conditional that checks to see whether a page > is (reserved | locked | not-dma-but-we-need-dma)? I really don't think it's that important! --Stephen -- This is a majordomo managed list. To unsubscribe, send a message with the body 'unsubscribe linux-mm me@address' to: majordomo@kvack.org