From owner-freebsd-hackers@FreeBSD.ORG Sun Dec 26 14:44:09 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B8D10106564A for ; Sun, 26 Dec 2010 14:44:09 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from mail-qy0-f182.google.com (mail-qy0-f182.google.com [209.85.216.182]) by mx1.freebsd.org (Postfix) with ESMTP id 6A66F8FC18 for ; Sun, 26 Dec 2010 14:44:08 +0000 (UTC) Received: by qyk36 with SMTP id 36so7594152qyk.13 for ; Sun, 26 Dec 2010 06:44:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:mime-version:sender:received :in-reply-to:references:from:date:x-google-sender-auth:message-id :subject:to:cc:content-type:content-transfer-encoding; bh=9ts8BMjbe4BbLMHcrIxeM4sag+rgmLhx38TSRb7shI8=; b=Cv4faTVBqcWOR/KT2F4KEuCZDzOC+WCObWAGVBrpNtEhz0FJW3MTgAt0cql0DutuT8 vwyHS+pvlOvXt/ZDk3SAjrKZ9rvap3TKCH1d7Pq5TS0wF53W2ta6CYqptncoDsE+/Tdl wsiG4hsls/FHaNIItlsvR81S7MytDbToobKUk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; b=IhY8M7bhW9WtSuy6ONCrndWQf8ZTUW4RO+Lz/ubb7AuRD0dtNeETcwS/TDoQw2VWSW UGD0IIzzx/yUePcTFjGwtrm6hv1JyLxsW1n2rd3wdeax4vZw5VBug5oqDfy5x/HOrctR dIZJGOZbN86EJt40FoDbZaa1bpiwppuLsTV9E= Received: by 10.229.190.204 with SMTP id dj12mr4013850qcb.101.1293373290124; Sun, 26 Dec 2010 06:21:30 -0800 (PST) MIME-Version: 1.0 Sender: ivoras@gmail.com Received: by 10.229.44.70 with HTTP; Sun, 26 Dec 2010 06:20:50 -0800 (PST) In-Reply-To: <20101226132431.GA16490@tops> References: <20101223224619.GA21984@tops> <20101226132431.GA16490@tops> From: Ivan Voras Date: Sun, 26 Dec 2010 15:20:50 +0100 X-Google-Sender-Auth: jwctn3du5m2mtshTi1eaHDCSVNI Message-ID: To: Gleb Kurtsou Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: freebsd-hackers@freebsd.org Subject: Re: [rfc] Replacing FNV and hash32 with Paul Hsieh's SuperFastHash X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 26 Dec 2010 14:44:09 -0000 On 26 December 2010 14:24, Gleb Kurtsou wrote: > On (25/12/2010 20:29), Ivan Voras wrote: >> On 23.12.2010 23:46, Gleb Kurtsou wrote: >> >> > For testing I've used dbench with 16 processes on 1 Gb swap back md >> > device, UFS + SoftUpdates: >> > Old hash (Mb/s): 599.94 =C2=A0600.096 599.536 >> > SFH hash (Mb/s): 612.439 612.341 609.673 >> > >> > It's just ~1% improvement, but dbench is not a VFS metadata intensive >> > benchmark. Subjectively it feels faster accessing maildir mailboxes >> > with ~10.000 messages : ) >> >> Try blogbench if you need metadata-intensive operations, or even fsx. > blogbench should be good, but I've always had hard time interpreting its > results. Besides results tend to very a lot, there is no way to set seed > value like in fsx, so that I could run exactly the same test in different > configurations. I think the exact sequence of blogbench operations depends on duration of previous operations (it's multithreaded) so from that angle you are right - you can't do a repeatable run except in the trivial cases. On the other hand, it uses rand() without seeding it with srand()/sranddev() so this part is actually very repeatable :) > fsx is a different beast, it reads/writes/truncates at random offsets - > great tool for debugging mmap/truncate issues. Patch doesn't improve it > in any way. It depends on what metadata operations you require - blogbench will create, find and write files (if we ignore atime); fsx will create a decent amount of traffic with file size and mtime changes. In your case you'll probably need to run it on a memory file system or tmpfs due to sensitivity to disk IO latencies (if your improvements is on the order of few percent).