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    SubjectRe: random minor benchmark: Re: Copy 20 tarfiles: ext2 vs (reiser4, unixfile) vs (reiser4,cryptcompress)
    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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