From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sun, 28 Jan 2007 16:48:06 +0100 From: Ingo Molnar Subject: Re: [PATCH] mm: remove global locks from mm/highmem.c Message-ID: <20070128154806.GA10615@elte.hu> References: <1169993494.10987.23.camel@lappy> <20070128144933.GD16552@infradead.org> <20070128151700.GA7644@elte.hu> <20070128152858.GA23410@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070128152858.GA23410@infradead.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Hellwig , Peter Zijlstra , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andrew Morton List-ID: * Christoph Hellwig wrote: > On Sun, Jan 28, 2007 at 04:17:00PM +0100, Ingo Molnar wrote: > > scalability. I did lock profiling on the -rt kernel, which exposes > > such things nicely. Half of the lock contention events during kernel > > compile were due to kmap(). (The system had 2 GB of RAM, so 40% > > lowmem, 60% highmem.) > > Numbers please, and not on -rt but on mainline. Please show the > profiles. i'm sorry, but do you realize that files_lock is a global lock, triggered by /every single/ file close? " files_lock is a global lock and we touch it for every single sys_close() system call that the system does. " You really dont need to be a rocket scientist to see that it's a globally bouncing cacheline that has a major effect on certain VFS-intense workloads. Peter has worked hard to eliminate its effects without having to couple this to an intrusive rewrite of the TTY layer. ( really, i personally find your dismissive style apalling and i think such a reception of a nice patchset must be humiliating to Peter. I certainly try to avoid to be involved with any VFS internals, due to this unwelcoming tone of discussion. Had you been around when i started contributing to the Linux kernel i'd probably not be hacking the kernel today. You are a good hacker but the simultaneous collateral damage you are causing is significantly reducing the net benefit. ) > > ps. please fix your mailer to not emit Mail-Followup-To headers. In > > Mutt you can do this via "set followup_to=no" in your .muttrc. > > I have told you last time that this is absolutely intentional and I > won't change it. ( You are messing up the reply headers, everyone is listed in the 'To:' field for any reply to your mail, instead of being added to the Cc: list. ) Ingo -- 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/ . Don't email: email@kvack.org