Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 23 Oct 2002 13:44:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 23 Oct 2002 13:44:06 -0400 Received: from e31.co.us.ibm.com ([32.97.110.129]:19089 "EHLO e31.co.us.ibm.com") by vger.kernel.org with ESMTP id ; Wed, 23 Oct 2002 13:44:02 -0400 To: Andi Kleen cc: akpm@digeo.com, linux-kernel@vger.kernel.org Reply-To: Gerrit Huizenga From: Gerrit Huizenga Subject: Re: [PATCH 2.5.43-mm2] New shared page table patch In-reply-to: Your message of 23 Oct 2002 05:03:38 +0200. MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <20680.1035395384.1@us.ibm.com> Date: Wed, 23 Oct 2002 10:49:44 -0700 Message-Id: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1671 Lines: 36 In message , > : Andi Kleen writes: > Gerrit Huizenga writes: > > > If the shared pte patch had mmap support, then all shared libraries > > would benefit. Might need to align them to 4 MB boundaries for best > > results, which would also be easy for libraries with unspecified > > attach addresses (e.g. most shared libraries). > > But only if the shared libraries are a multiple of 2/4MB, otherwise you'll > waste memory. Or do you propose to link multiple mmap'ed libraries together > into the same page ? Hmm. I didn't propose. Sounds cool. But that would have to happen at the compiler's loader level, not the dynamic linker side of things, which makes it less likely. Someone once proposed a mega-library where the big/key shared objects were linked together which would make this somewhat more practical. But even wasting a bit of space for a few key libraries, even if they are smaller than 4 MB (or 2 MB) on ia32 (ia32 PAE) might be worth a bit of TLB & general overhead (e.g. like the kernel text pages). And, if shared, even a bigger win. > But I agree it would be nice to have a chattr for files that tells > mmap() to use large pages for them. Yep - that would be ideal - like the old sticky flag on binaries. As a patch, that would make it easy to compare performance diffs as well. Probably good for things like Oracle or DB2 as well. gerrit - 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/