From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f45.google.com ([209.85.215.45]:35722 "EHLO mail-lf0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751487AbcF3Sld (ORCPT ); Thu, 30 Jun 2016 14:41:33 -0400 Received: by mail-lf0-f45.google.com with SMTP id l188so61773239lfe.2 for ; Thu, 30 Jun 2016 11:41:32 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Srinath Krishna Ananthakrishnan Date: Thu, 30 Jun 2016 11:35:29 -0700 Message-ID: Subject: Re: Compression options in fio Content-Type: text/plain; charset=UTF-8 Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Sitsofe Wheeler Cc: "fio@vger.kernel.org" Another idiosyncrasy that I observed was, With rw=write, compression options are not heeded. They seem to work only rw=rw. Thanks, Srinath On Thu, Jun 30, 2016 at 10:58 AM, Srinath Krishna Ananthakrishnan wrote: > I don't want fio to vary the data and need it to be more deterministic. > > After playing with it for quite some time, I have the following > (inconclusive) theory. > > 1. If no verify options are set, fio generates > buffer_compress_percentage worth of compressible data per block size. > Compressible data is always zeroed out. > 2. With verify options, fio generates buffer_compress_percentage worth > of compressible data (zeroes) for some blocks but there are these > bunch of blocks from time to time that contain purely random data. > > From the manual, verify options add additional meta data to the header > of every block for verification but I'm not sure why some blocks turn > out to be completely random with this setting on. I tried multiple > verify hashes with the same result. > > With either of the cases, I don't seem to get the buffer_pattern > setting working. > > > Thanks, > Srinath > > > On Mon, Jun 27, 2016 at 10:16 PM, Sitsofe Wheeler wrote: >> On 27 June 2016 at 21:41, Srinath Krishna Ananthakrishnan wrote: >>> >>> [small_write] >>> rw=rw >>> blocksize=4k >>> size=100M >>> verify=crc32c-intel >>> buffer_compress_percentage=50 >>> buffer_pattern="abcd" >>> >>> With this, I don't see fio generating compressible data with the >>> pattern and still reverts to generating random data. Anything I'm >>> missing? >> >> You're forcing the pattern of data that must be used via >> buffer_pattern so you aren't you taking away the ability for fio to >> vary the data? Do you get a different result if you don't specify >> buffer_pattern ? >> >> -- >> Sitsofe | http://sucs.org/~sits/