Josh Berkus wrote: > On 12/6/10 6:13 PM, Tom Lane wrote: > > Josh Berkus <j...@agliodbs.com> writes: > >> OK, patch coming then. Right now test_fsync aborts when O_DIRECT fails. > >> What should I have it do instead? > > > > Report that it fails, and keep testing the other methods. > > Patch attached. Includes a fair amount of comment cleanup, since > existing comments did not meet our current project standards. Tests all > 6 of the methods we support separately. > > Some questions, though: > > (1) Why are we doing the open_sync different-size write test? AFAIK, > this doesn't match any behavior which PostgreSQL has.
I did that so we could see the impact of doing 2 8k writes that were both fsync'ed vs doing one 16k write and then fsync: Compare open_sync with different sizes: open_sync 16k write 201.323/second 2 open_sync 8k writes 332.466/second We often write multiple 8k WAL pages and then fsync on commit. > (2) In this patch, I'm stepping down the number of loops which > fsync_writethrough does by 90%. The reason for that was that on the > platforms where I tested writethrough (desktop machines), doing 10,000 > loops took 15-20 *minutes*, which seems hard on the user. Would be easy > to revert if you think it's a bad idea. > Possibly auto-sizing the number of loops based on the first fsync test > might be a good idea, but seems like going a bit too far. Sure, I recently increased the number, probably too much. > (3) Should the multi-descriptor test be using writethrough on platforms > which support it? Uh, I didn't think that would matter because the test is to test kernel behavior of writing to one file descriptor and fsyncing using another. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers