From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261615AbUKIShz (ORCPT ); Tue, 9 Nov 2004 13:37:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261617AbUKIShy (ORCPT ); Tue, 9 Nov 2004 13:37:54 -0500 Received: from [12.177.129.25] ([12.177.129.25]:11204 "EHLO ccure.user-mode-linux.org") by vger.kernel.org with ESMTP id S261615AbUKISgW (ORCPT ); Tue, 9 Nov 2004 13:36:22 -0500 Message-Id: <200411092048.iA9Kmjg9004223@ccure.user-mode-linux.org> X-Mailer: exmh version 2.4 06/23/2000 with nmh-1.1-RC1 To: Blaisorblade cc: user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, cw@f00f.org Subject: Re: Synchronization primitives in UML (was: Re: [uml-devel] Re: [patch 09/20] uml: use SIG_IGN for empty sighandler) In-Reply-To: Your message of "Tue, 09 Nov 2004 18:44:35 +0100." <200411091844.44218.blaisorblade_spam@yahoo.it> References: <200411052036.55541.blaisorblade_spam@yahoo.it> <20041106051306.GA3038@ccure.user-mode-linux.org> <200411091844.44218.blaisorblade_spam@yahoo.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Tue, 09 Nov 2004 15:48:45 -0500 From: Jeff Dike Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org blaisorblade_spam@yahoo.it said: > I also understand now what all this is for. When I have time for this, > I'll at least copy and paste your mail into a comment, with any > needed adjustment. That would be a good idea. > For the semaphore issue, I have some ideas (like using futexes) which > need to be developed a bit: > 1) I want to create a semaphore API in os_*. > 2) It will be able to use socketpairs. > 3) It will be able to use futexes, if they are > non-persistant and usable without too much issues (the same way we > are going to support Async I/O). > 4) It will be used first by the code > which could really benefit from the performance increase. > 5) It won't > use persistant objects. This all sounds good, although there are simplicity benefits to just using one underlying mechanism, as long as there are no overriding disadvantages to it. > Any comment on these issues? Also, apart TT context switching, is > there any other performance-sensitive use of semaphores, which would > benefit from using futexes? Offhand, I think context switching is the most sensitive one. > Yes, semget and friends are uglier. > But don't think that the current nested code is simple to read - three > semaphores at a time, without a clear name, are not the clearer code > on the world. What nested code are you talking about? Jeff From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.12] helo=sc8-sf-mx2.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1CRaqr-0004D2-B0 for user-mode-linux-devel@lists.sourceforge.net; Tue, 09 Nov 2004 10:36:21 -0800 Received: from [12.177.129.25] (helo=ccure.user-mode-linux.org) by sc8-sf-mx2.sourceforge.net with esmtp (TLSv1:DES-CBC3-SHA:168) (Exim 4.41) id 1CRaqo-0006G9-Hy for user-mode-linux-devel@lists.sourceforge.net; Tue, 09 Nov 2004 10:36:20 -0800 Message-Id: <200411092048.iA9Kmjg9004223@ccure.user-mode-linux.org> Subject: Re: Synchronization primitives in UML (was: Re: [uml-devel] Re: [patch 09/20] uml: use SIG_IGN for empty sighandler) In-Reply-To: Your message of "Tue, 09 Nov 2004 18:44:35 +0100." <200411091844.44218.blaisorblade_spam@yahoo.it> References: <200411052036.55541.blaisorblade_spam@yahoo.it> <20041106051306.GA3038@ccure.user-mode-linux.org> <200411091844.44218.blaisorblade_spam@yahoo.it> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii From: Jeff Dike Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Tue, 09 Nov 2004 15:48:45 -0500 To: Blaisorblade Cc: user-mode-linux-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, cw@f00f.org blaisorblade_spam@yahoo.it said: > I also understand now what all this is for. When I have time for this, > I'll at least copy and paste your mail into a comment, with any > needed adjustment. That would be a good idea. > For the semaphore issue, I have some ideas (like using futexes) which > need to be developed a bit: > 1) I want to create a semaphore API in os_*. > 2) It will be able to use socketpairs. > 3) It will be able to use futexes, if they are > non-persistant and usable without too much issues (the same way we > are going to support Async I/O). > 4) It will be used first by the code > which could really benefit from the performance increase. > 5) It won't > use persistant objects. This all sounds good, although there are simplicity benefits to just using one underlying mechanism, as long as there are no overriding disadvantages to it. > Any comment on these issues? Also, apart TT context switching, is > there any other performance-sensitive use of semaphores, which would > benefit from using futexes? Offhand, I think context switching is the most sensitive one. > Yes, semget and friends are uglier. > But don't think that the current nested code is simple to read - three > semaphores at a time, without a clear name, are not the clearer code > on the world. What nested code are you talking about? Jeff ------------------------------------------------------- This SF.Net email is sponsored by: Sybase ASE Linux Express Edition - download now for FREE LinuxWorld Reader's Choice Award Winner for best database on Linux. http://ads.osdn.com/?ad_id=5588&alloc_id=12065&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel