From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755229AbYFAHYY (ORCPT ); Sun, 1 Jun 2008 03:24:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751256AbYFAHYP (ORCPT ); Sun, 1 Jun 2008 03:24:15 -0400 Received: from extu-mxob-1.symantec.com ([216.10.194.28]:49791 "EHLO extu-mxob-1.symantec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751175AbYFAHYO (ORCPT ); Sun, 1 Jun 2008 03:24:14 -0400 Date: Sun, 1 Jun 2008 08:23:43 +0100 (BST) From: Hugh Dickins X-X-Sender: hugh@blonde.site To: Andrew Morton cc: Pavel Machek , kernel list , "Rafael J. Wysocki" Subject: Re: sync_file_range(SYNC_FILE_RANGE_WRITE) blocks? In-Reply-To: <20080531173950.c4f04028.akpm@linux-foundation.org> Message-ID: References: <20080530102619.GA2468@elf.ucw.cz> <20080530204307.GA4978@ucw.cz> <20080531173950.c4f04028.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 31 May 2008, Andrew Morton wrote: > On Sat, 31 May 2008 19:44:49 +0100 (BST) Hugh Dickins wrote: > > > > All I can say so far is that I find the same as you do: > > SYNC_FILE_RANGE_WRITE (after writing) takes a significant amount of time, > > more than half as long as when you add in SYNC_FILE_RANGE_WAIT_AFTER too. > > > > Which make the sync_file_range call pretty pointless: your usage seems > > perfectly reasonable to me, but somehow we've broken its behaviour. > > I'll be investigating ... > > It will block on disk queue fullness - sysrq-W will tell. Ah, thank you. What a disappointment, though it's understandable. Doesn't that very severely limit the usefulness of the system call? I admit the flag isn't called SYNC_FILE_RANGE_WRITE_WITHOUT_WAITING, but I don't suppose Pavel and I are the only ones misled by it. Hugh