From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756168AbbDOKnZ (ORCPT ); Wed, 15 Apr 2015 06:43:25 -0400 Received: from cantor2.suse.de ([195.135.220.15]:42656 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754298AbbDOKnE (ORCPT ); Wed, 15 Apr 2015 06:43:04 -0400 From: Mel Gorman To: Linux-MM Cc: Rik van Riel , Johannes Weiner , Dave Hansen , Andi Kleen , LKML , Mel Gorman Subject: [PATCH 3/4] mm: Gather more PFNs before sending a TLB to flush unmapped pages Date: Wed, 15 Apr 2015 11:42:55 +0100 Message-Id: <1429094576-5877-4-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 2.1.2 In-Reply-To: <1429094576-5877-1-git-send-email-mgorman@suse.de> References: <1429094576-5877-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The patch "mm: Send a single IPI to TLB flush multiple pages when unmapping" would batch 32 pages before sending an IPI. This patch increases the size of the data structure to hold a pages worth of PFNs before sending an IPI. This is a trade-off between memory usage and reducing IPIS sent. In the ideal case where multiple processes are reading large mapped files, this patch reduces interrupts/second from roughly 180K per second to 60K per second. Signed-off-by: Mel Gorman --- include/linux/sched.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 9d51841806f4..abff66ecc302 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1275,11 +1275,16 @@ enum perf_event_task_context { perf_nr_task_contexts, }; -/* Matches SWAP_CLUSTER_MAX but refined to limit header dependencies */ -#define BATCH_TLBFLUSH_SIZE 32UL +/* + * Use a page to store as many PFNs as possible for batch unmapping. Adjusting + * this trades memory usage for number of IPIs sent + */ +#define BATCH_TLBFLUSH_SIZE \ + ((PAGE_SIZE - sizeof(struct cpumask) - sizeof(unsigned long)) / sizeof(unsigned long)) /* Track pages that require TLB flushes */ struct unmap_batch { + /* Update BATCH_TLBFLUSH_SIZE when adjusting this structure */ struct cpumask cpumask; unsigned long nr_pages; unsigned long pfns[BATCH_TLBFLUSH_SIZE]; -- 2.1.2