Messages in this thread | | | Date | Thu, 26 Jan 2006 23:41:15 +0300 | From | Edward Shishkin <> | Subject | Re: random minor benchmark: Re: Copy 20 tarfiles: ext2 vs (reiser4, unixfile) vs (reiser4,cryptcompress) |
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Jens Axboe wrote:
>On Thu, Jan 26 2006, Edward Shishkin wrote: > > >>Jens Axboe wrote: >> >> >> >>>On Wed, Jan 25 2006, Hans Reiser wrote: >>> >>> >>> >>> >>>>Notice how CPU speed (and number of cpus) completely determines >>>>compression performance. >>>> >>>>cryptcompress refers to the reiser4 compression plugin, (unix file) >>>>refers to the reiser4 non-compressing plugin. >>>> >>>>Edward Shishkin wrote: >>>> >>>> >>>> >>>> >>>> >>>>>Here are the tests that vs asked for: >>>>>Creation (dd) of 20 tarfiles (the original 200M file is in ramfs) >>>>>Kernel: 2.6.15-mm4 + current git snapshot of reiser4 >>>>> >>>>>------------------------------------------ >>>>> >>>>>Laputa workstation >>>>>Uni Intel Pentium 4 (2.26 GHz) 512M RAM >>>>> >>>>>ext2: >>>>>real 2m, 15s >>>>>sys 0m, 14s >>>>> >>>>>reiser4(unix file) >>>>>real 2m, 7s >>>>>sys 0m, 23s >>>>> >>>>>reiser4(cryptcompress, lzo1, 64K) >>>>>real 2m, 13s >>>>>sys 0m, 11s >>>>> >>>>> >>>>> >>>>> >>>Just curious - does your crypt plugin reside in user space? >>> >>> >>> >>> >>> >>Nop. >>This is just wrappers for linux crypto api, zlib, etc.. >>so user time is zero and not interesting. >> >> > >Then why is the sys time lower than the "plain" writes on ext2 and >reiser4? Surely compressing isn't for free, yet the sys time is lower on >the compression write than the others. > > >
I guess this is because real compression is going in background flush, not in sys_write->write_cryptcompress (which just copies user's data to page cache). So in this case we have something very similar to ext2. Reiser4 plain write (write_unix_file) is more complex, and currently we try to reduce its sys time.
Edward.
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