From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans Reiser Subject: Re: Reiser4 und LZO compression Date: Tue, 29 Aug 2006 10:56:59 -0700 Message-ID: <44F47FEB.9060005@namesys.com> References: <20060827003426.GB5204@martell.zuzino.mipt.ru> <44F322A6.9020200@namesys.com> <20060828173721.GA11332@hello-penguin.com> <44F332D6.6040209@namesys.com> <1156801705.2969.6.camel@nigel.suspend2.net> <20060829045937.GA9181@localhost.hsdv.com> <20060829143814.GA21868@hello-penguin.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: List-Id: Content-Type: text/plain; charset="us-ascii" To: PFC Cc: "reiserfs-list@namesys.com" PFC, thanks for giving us some real data. May I post it to the lkml thread? In essence, LZO wins the benchmarks, and the code is hard to read. I guess I have to go with LZO, and encourage people to take a stab at dethroning it. Hans PFC wrote: > > I have made a little openoffice spreadsheet with the results. > You can have fun entering stuff and seeing the results. > > http://peufeu.free.fr/compression.ods > > Basically, a laptop having the same processor as my PC and a > crummy 15 MB/s drive (like most laptop drives) will get a 2.5x speedup > using lzf, while using 40% CPU for compression and 15% CPU for > decompression. I'd say it's a clear, huuuuge win. > > A desktop computer with a modern IDE drive doing 50 MB/s will > still get nice speedups (1.8x on write, 2.5x on read) but of course, > more CPU will be used because of the higher throughput. In this case > it is CPU limited on compression and disk limited on decompression. > However soon everyone will have dual core monsters so... > > A big ass RAID will not get much benefit unless : > - the buffer cache stores compressed pages, so compression > virtually doubles the RAM cache > - or the CPU is really fast > - or you put one of these neat FPGA modules in a free Opteron > socket and upload a soft-hardware LZF in it with a few gigabytes/s > throughput Or you look the sysadmin in the eyes, and say, your file servers have more out of disk space problems than load problems, yes? > > ... > >