From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id B038E6B003D for ; Thu, 12 Mar 2009 17:30:22 -0400 (EDT) Date: Thu, 12 Mar 2009 21:30:06 +0000 From: Russell King - ARM Linux Subject: Re: [PATCH] [ARM] Flush only the needed range when unmapping a VMA Message-ID: <20090312213006.GN7854@n2100.arm.linux.org.uk> References: <49B54B2A.9090408@nokia.com> <1236690093-3037-1-git-send-email-Aaro.Koskinen@nokia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1236690093-3037-1-git-send-email-Aaro.Koskinen@nokia.com> Sender: owner-linux-mm@kvack.org To: Aaro Koskinen Cc: linux-arm-kernel@lists.arm.linux.org.uk, linux-mm@kvack.org, hugh@veritas.com List-ID: On Tue, Mar 10, 2009 at 03:01:33PM +0200, Aaro Koskinen wrote: > When unmapping N pages (e.g. shared memory) the amount of TLB flushes > done can be (N*PAGE_SIZE/ZAP_BLOCK_SIZE)*N although it should be N at > maximum. With PREEMPT kernel ZAP_BLOCK_SIZE is 8 pages, so there is a > noticeable performance penalty when unmapping a large VMA and the system > is spending its time in flush_tlb_range(). It would be nice to have some figures for the speedup gained by this optimisation - is there any chance you could provide a comparison? -- 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