From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 3 Aug 2001 20:35:14 -0700 (PDT) From: Linus Torvalds Subject: Re: [RFC][DATA] re "ongoing vm suckage" In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Rik van Riel Cc: Daniel Phillips , Ben LaHaise , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Sat, 4 Aug 2001, Rik van Riel wrote: > On Fri, 3 Aug 2001, Linus Torvalds wrote: > > > Please just remove the code instead. I don't think it buys you anything. > > IIRC you applied the patch introducing that logic because it > gave a 25% performance increase under some write intensive > loads (or something like that). That's the batching code, which is somewhat intertwined with the same code. The batching code is a separate issue: when we free the requests, we don't actually make them available as they get free'd (because then the waiters will trickle out new requests one at a time and cannot do any merging etc). Also, the throttling code probably _did_ make behaviour nicer back when "sync()" used to use ll_rw_block(). Of course, now most of the IO layer actually uses "submit_bh()" and bypasses this code completely, so only the ones that still use it get hit by the unfairness. What a double whammy ;) Linus -- 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/