On Thu, Jan 26 2006, Hans Reiser wrote: > Edward Shishkin wrote: > > > > > 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. > > > > > > > > > Which means that only real time is a meaningful measurement.....
Indeed. I guess the compression stuff cost is hard to quantify, since it has cache effects on the rest of the system in addition to costing CPU cycles on its own. A profile of, say, dbench with and without compression would be interesting to see. And the actual dbench reults, naturally :-) -- Jens Axboe
