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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