ZFS is designed to "sync" a transaction group about every 5 seconds under normal work loads. So your system looks to be operating as designed. Is there some specific reason why you need to reduce this interval? In general, this is a bad idea, as there is somewhat of a "fixed overhead" associated with each sync, so increasing the sync frequency could result in increased IO.
-Mark Tharindu Rukshan Bamunuarachchi wrote: > Dear ZFS Gurus, > > We are developing low latency transaction processing systems for stock > exchanges. > Low latency high performance file system is critical component of our > trading systems. > > We have choose ZFS as our primary file system. > But we saw periodical disk write peaks every 4-5 second. > > Please refer first column of below output. (marked in bold) > Output is generated from our own Disk performance measuring tool. i.e > DTool (please find attachment) > > Compared UFS/VxFS , ZFS is performing very well, but we could not > minimize periodical peaks. > We used autoup and tune_r_fsflush flags for UFS tuning. > > Are there any ZFS specific tuning, which will reduce file system flush > interval of ZFS. > > I have tried all parameters specified in "solarisinternals" and google.com. > I would like to go for ZFS code change/recompile if necessary. > > Please advice. > > Cheers > Tharindu > > > > cpu4600-100 /tantan >./*DTool -f M -s 1000 -r 10000 -i 1 -W* > System Tick = 100 usecs > Clock resolution 10 > HR Timer created for 100usecs > z_FileName = M > i_Rate = 10000 > l_BlockSize = 1000 > i_SyncInterval = 0 > l_TickInterval = 100 > i_TicksPerIO = 1 > i_NumOfIOsPerSlot = 1 > Max (us)| Min (us) | Avg (us) | MB/S | File > Freq Distribution > 336 | 4 | 10.5635 | 4.7688 | M > 50(98.55), 200(1.09), 500(0.36), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > *1911 * | 4 | 10.3152 | 9.4822 | M > 50(98.90), 200(0.77), 500(0.32), 2000(0.01), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 307 | 4 | 9.9386 | 9.5324 | M > 50(99.03), 200(0.66), 500(0.31), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 331 | 4 | 9.9465 | 9.5332 | M > 50(99.04), 200(0.72), 500(0.24), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 318 | 4 | 10.1241 | 9.5309 | M > 50(99.07), 200(0.66), 500(0.27), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 303 | 4 | 9.9236 | 9.5296 | M > 50(99.13), 200(0.59), 500(0.28), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 560 | 4 | 10.2604 | 9.4565 | M > 50(98.82), 200(0.86), 500(0.31), 2000(0.01), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 376 | 4 | 9.9975 | 9.5176 | M > 50(99.05), 200(0.63), 500(0.32), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > *9783 * | 4 | 10.8216 | 9.5301 | M > 50(99.05), 200(0.58), 500(0.36), 2000(0.00), 5000(0.00), 10000(0.01), > 100000(0.00), 200000(0.00), > 332 | 4 | 9.9345 | 9.5252 | M > 50(99.06), 200(0.61), 500(0.33), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 355 | 4 | 9.9906 | 9.5315 | M > 50(99.01), 200(0.69), 500(0.30), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 356 | 4 | 10.2341 | 9.5207 | M > 50(98.96), 200(0.76), 500(0.28), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > 320 | 4 | 9.8893 | 9.5279 | M > 50(99.10), 200(0.59), 500(0.31), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > *10005* | 4 | 10.8956 | 9.5258 | M > 50(99.07), 200(0.63), 500(0.29), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.01), 200000(0.00), > 308 | 4 | 9.8417 | 9.5312 | M > 50(99.07), 200(0.64), 500(0.29), 2000(0.00), 5000(0.00), 10000(0.00), > 100000(0.00), 200000(0.00), > > > ------------------------------------------------------------------------ > > ******************************************************************************************************************************************************************* > > "The information contained in this email including in any attachment is > confidential and is meant to be read only by the person to whom it is > addressed. If you are not the intended recipient(s), you are prohibited from > printing, forwarding, saving or copying this email. If you have received this > e-mail in error, please immediately notify the sender and delete this e-mail > and its attachments from your computer." > > ******************************************************************************************************************************************************************* > > > ------------------------------------------------------------------------ > > _______________________________________________ > zfs-code mailing list > zfs-code at opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-code
