Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751714Ab0HQEfb (ORCPT ); Tue, 17 Aug 2010 00:35:31 -0400 Received: from smtp-out.google.com ([216.239.44.51]:43173 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751175Ab0HQEfQ convert rfc822-to-8bit (ORCPT ); Tue, 17 Aug 2010 00:35:16 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=mime-version:in-reply-to:references:date:message-id:subject:from:to: cc:content-type:content-transfer-encoding:x-system-of-record; b=Qsq87GUL6W5ruqCV7ZMd81iFsZqMSmY13hWJ0V/xsp9RUBaMMWLRiR597iyG9Rn4h huRTAyk7Qcxr3/LE68Zvg== MIME-Version: 1.0 In-Reply-To: <1281992801.1926.2019.camel@laptop> References: <20100816182834.3541.42317.stgit@bumblebee1.mtv.corp.google.com> <1281987236.1926.1895.camel@laptop> <1281992801.1926.2019.camel@laptop> Date: Mon, 16 Aug 2010 21:35:09 -0700 Message-ID: Subject: Re: [PATCH] Fixed a mismatch between the users of radix_tree and the implementation. From: Salman Qazi To: Peter Zijlstra Cc: paulmck@us.ibm.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, adurbin@google.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2144 Lines: 66 On Mon, Aug 16, 2010 at 2:06 PM, Peter Zijlstra wrote: > (html damaged email alert) > > On Mon, 2010-08-16 at 13:59 -0700, Salman Qazi wrote: >> On Mon, Aug 16, 2010 at 12:33 PM, Peter Zijlstra wrote: >> ? ? ? ? On Mon, 2010-08-16 at 11:30 -0700, Salman Qazi wrote: >> ? ? ? ? > For the delete case, >> ? ? ? ? > we no longer shrink the tree back to being just the root containing the >> ? ? ? ? > only remaining object. ?For the insert case, we no longer store the >> ? ? ? ? > first object in the root, rather allocating a node structure for it. ?The >> ? ? ? ? > reason that this works is that deleting (or inserting) intermediate nodes >> ? ? ? ? > does not make a difference to a reader holding a slot. >> >> >> ? ? ? ? Ah, I through that was what it did. So you basically increase the memory >> ? ? ? ? footprint for tiny files.. have you done any measurements on that? >> > >> You raise a valid concern. ?I haven't. ?What would you recommend as a >> benchmark/metric to measure this? > > One thing you could try is something like the below on a freshly booted > machine, once without and once with the patch: > > ?cd /usr/src/linux-2.6 > ?echo 1 > /proc/sys/vm/drop_caches > ?grep radix /proc/slabinfo > ?make bzImage > ?echo 1 > /proc/sys/vm/drop_caches > ?grep radix /proc/slabinfo > > > > Here's what I see: Without the patch: Before: radix_tree_node 468 1400 568 28 4 : tunables 0 0 0 : slabdata 50 50 0 After: radix_tree_node 1886 3192 568 28 4 : tunables 0 0 0 : slabdata 114 114 0 With the patch: Before: radix_tree_node 495 1176 568 28 4 : tunables 0 0 0 : slabdata 42 42 0 After: radix_tree_node 3173 7336 568 28 4 : tunables 0 0 0 : slabdata 262 262 0 So, not particularly good news :(. -- 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/