On 06/29/2011 02:33 PM, Sašo Kiselkov wrote: >> Also there is a buffer-size limit, like this (384Mb): >> set zfs:zfs_write_limit_override = 0x18000000 >> >> or on command-line like this: >> # echo zfs_write_limit_override/W0t402653184 | mdb -kw > > Currently my value for this is 0. How should I set it? I'm writing > ~15MB/s and would like txg flushes to occur at most once every 10 > seconds. Should I set it to 150MB then? > >> We had similar spikes with big writes to a Thumper with SXCE in the pre-90's >> builds, when the system would stall for seconds while flushing a 30-second >> TXG >> full of data. Adding a reasonable megabyte limit solved the unresponsiveness >> problem for us, by making these flush-writes rather small and quick. > > I need to do the opposite - I don't need to shorten the interval of > writes, I need to increase it. Can I do that using zfs_write_limit_override?
Just as a folloup, I've had a look at the tunables in dsl_pool.c and found that I could potentially influence the write pressure calculation by tuning zfs_txg_synctime_ms - do you think increasing this value from its default (1000ms) help me lower the write scheduling frequency? (I don't mind if a txg write takes even twice as long, my application buffers are on average 6 seconds long.) Regards, -- Saso _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
