Re: Comparison of PgSQL Performance on HAMMER and UFS

[Jan.Lentfer@xxxxxx]

Zitat von Matthew Dillon <dillon@apollo.backplane.com>:

>     I'd like to see how those results compare with the various
>     MPSAFE sysctls turned on, and also with fsync disabled (so
>     we can get an idea how badly fsync effects write transactions,
>     since we know fsync is very expensive on HAMMER):
>
>     vfs.getattr_mpsafe=1
>     vfs.read_mpsafe=1
>
>     And
>
>     vfs.hammer.fsync_mode=2
>
>     And also with the recent buffer cache work on master.
>     The meta-data for a 5GB dataset should be cachable but
>     prior to the work buffer cache data was being thrown out
>     of the backing VM page caches too quickly.
>
>     Another thing we know about HAMMER is that the initial
>     B-Tree layout is pretty horrible.  It takes a reblocking
>     pass to fix it up.  It shouldn't effect a dataset that
>     small with the cache priorities fixed in master, though.
>
> 						-Matt

I redid the tests as suggested and with a slighlty different test  
setup. Results attached. Next step: Redo the tests on -DEVELOPMENT.

Regards,

Jan




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