From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cantor2.suse.de ([195.135.220.15]:37658 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757036AbaGAOoR (ORCPT ); Tue, 1 Jul 2014 10:44:17 -0400 Date: Tue, 1 Jul 2014 16:44:15 +0200 From: David Sterba To: Sergey Senozhatsky Cc: Chris Mason , Josef Bacik , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] btrfs compression: merge inflate and deflate z_streams Message-ID: <20140701144415.GJ1553@suse.cz> Reply-To: dsterba@suse.cz References: <1404142330-1621-1-git-send-email-sergey.senozhatsky@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1404142330-1621-1-git-send-email-sergey.senozhatsky@gmail.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Tue, Jul 01, 2014 at 12:32:10AM +0900, Sergey Senozhatsky wrote: > `struct workspace' used for zlib compression contains two zlib > z_stream-s: `def_strm' used in zlib_compress_pages(), and `inf_strm' > used in zlib_decompress/zlib_decompress_biovec(). None of these > functions use `inf_strm' and `def_strm' simultaniously, meaning that > for every compress/decompress operation we need only one z_stream > (out of two available). > > `inf_strm' and `def_strm' are different in size of ->workspace. For > inflate stream we vmalloc() zlib_inflate_workspacesize() bytes, for > deflate stream - zlib_deflate_workspacesize() bytes. On my system zlib > returns the following workspace sizes, correspondingly: 42312 and 268104 > (+ guard pages). > > Keep only one `z_stream' in `struct workspace' and use it for both > compression and decompression. Hence, instead of vmalloc() of two > z_stream->worskpace-s, allocate only one of size: > max(zlib_deflate_workspacesize(), zlib_inflate_workspacesize()) > > Signed-off-by: Sergey Senozhatsky Reviewed-by: David Sterba