Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030418AbWASBti (ORCPT ); Wed, 18 Jan 2006 20:49:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030501AbWASBti (ORCPT ); Wed, 18 Jan 2006 20:49:38 -0500 Received: from viper.oldcity.dca.net ([216.158.38.4]:35237 "HELO viper.oldcity.dca.net") by vger.kernel.org with SMTP id S1030418AbWASBth (ORCPT ); Wed, 18 Jan 2006 20:49:37 -0500 Subject: Re: 2.6.15-rc5: latency regression vs 2.6.14 in exit_mmap->free_pgtables From: Lee Revell To: Hugh Dickins Cc: linux-kernel , Ingo Molnar , Linus Torvalds In-Reply-To: References: <1135726300.22744.25.camel@mindpipe> Content-Type: text/plain Date: Wed, 18 Jan 2006 20:42:39 -0500 Message-Id: <1137634961.626.2.camel@mindpipe> Mime-Version: 1.0 X-Mailer: Evolution 2.5.4 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1317 Lines: 30 On Wed, 2005-12-28 at 22:59 +0000, Hugh Dickins wrote: > I'm to blame for that - sorry. It didn't occur to me that I was > moving any signficant amount of work (on mms with many vmas) into the > section with preemption disabled. Actually, the mm->page_table_lock > is _not_ held there any more; but preemption is still disabled while > using the per-cpu mmu_gathers. > > I wish you'd found it at -rc1 time. It's not something that can > be properly corrected in a hurry. The proper fix is to rework the > tlb_gather_mmu stuff, so it can be done without preemption disabled. > It's already a serious limitation in unmap_vmas, with CONFIG_PREEMPT's > ZAP_BLOCK_SIZE spoiling throughput with far too many TLB flushes. > > On my list to work on; but the TLB always needs great care, and this > goes down into architectural divergences, with truncation of a mapped > file adding further awkward constraints. I imagine 2.6.16-rc1 is only > a couple of weeks away, so it's unlikely to be fixed in 2.6.16 either. > Hugh, Is this believed to be fixed in 2.6.16-rc1? Lee - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/