From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f171.google.com (mail-ie0-f171.google.com [209.85.223.171]) by kanga.kvack.org (Postfix) with ESMTP id BB2026B004D for ; Tue, 25 Feb 2014 13:35:37 -0500 (EST) Received: by mail-ie0-f171.google.com with SMTP id to1so718436ieb.16 for ; Tue, 25 Feb 2014 10:35:37 -0800 (PST) Received: from merlin.infradead.org (merlin.infradead.org. [2001:4978:20e::2]) by mx.google.com with ESMTPS id k1si39542776igj.22.2014.02.25.10.35.35 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 25 Feb 2014 10:35:35 -0800 (PST) Date: Tue, 25 Feb 2014 19:35:22 +0100 From: Peter Zijlstra Subject: Re: [PATCH v2] mm: per-thread vma caching Message-ID: <20140225183522.GU6835@laptop.programming.kicks-ass.net> References: <1393352206.2577.36.camel@buesod1.americas.hpqcorp.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1393352206.2577.36.camel@buesod1.americas.hpqcorp.net> Sender: owner-linux-mm@kvack.org List-ID: To: Davidlohr Bueso Cc: Andrew Morton , Ingo Molnar , Linus Torvalds , Michel Lespinasse , Mel Gorman , Rik van Riel , KOSAKI Motohiro , aswin@hp.com, scott.norton@hp.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Tue, Feb 25, 2014 at 10:16:46AM -0800, Davidlohr Bueso wrote: > +void vmacache_update(struct mm_struct *mm, unsigned long addr, > + struct vm_area_struct *newvma) > +{ > + /* > + * Hash based on the page number. Provides a good > + * hit rate for workloads with good locality and > + * those with random accesses as well. > + */ > + int idx = (addr >> PAGE_SHIFT) & 3; % VMACACHE_SIZE perhaps? GCC should turn that into a mask for all sensible values I would think. Barring that I think something like: #define VMACACHE_BITS 2 #define VMACACHE_SIZE (1U << VMACACHE_BITS) #define VMACACHE_MASK (VMACACHE_SIZE - 1) Might do I suppose. > + current->vmacache[idx] = newvma; > +} > -- > 1.8.1.4 > > > -- 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