If you execute pragma synchronous = off;
you'll be able to compare performance with syncs and without them. So if you make this comparison on standard spinning disk and on SSD you'll see if syncs on SSD indeed extra-ordinary slow. Pavel On Wed, Sep 23, 2009 at 10:09 AM, Mark <godef...@gmail.com> wrote: > It's very possible, but I don't know how to tell. Is there an easy way > to know if the sync() calls are taking inordinately long? > > Mark > > > Thomas Briggs wrote: >> Is the sync necessary to commit a transaction slow? Performance of >> that sync depends on the OS, file system, hardwar, etc. IIRC, so IOs >> may be fast but it's possible that the syncs are killing you. >> >> -T >> >> On Tue, Sep 22, 2009 at 5:14 PM, Mark <godef...@gmail.com> wrote: >>> Lothar Scholz wrote: >>>> Hello Mark, >>>> >>>> Tuesday, September 22, 2009, 3:53:48 AM, you wrote: >>>> >>>> M> I've currently got a loaner high-performance flash-based "SSD" (let's >>>> M> just say it doesn't connect to any disk controllers) that I'm testing >>>> M> for performance. I've run my application against it, and I believe that >>>> M> I should see numbers MUCH higher than I do. When I run my test app on a >>>> M> normal SATA 7200 RPM disk, I get a certain performance, and on the "SSD" >>>> M> I get about 1/10th that speed. On an array of SAS disks I get numbers >>>> M> that are about 5x faster than my SATA disk, so my software itself isn't >>>> M> (I believe) the bottleneck. >>>> >>>> M> I'm wondering if anyone has any tips for "optimizing" for this sort of >>>> M> storage solution. >>>> >>>> Throw it into the trash bin and buy a new one which has a 3rd >>>> generation controller and at least 64MB fast cache. The old JMicron >>>> controller that many low cost SSD still use was developed for Flash >>>> USB sticks. >>>> >>>> With modern SSD like the latest Samsung should give you at least the >>>> same performance as the SATA. If it gets better depends on file size >>>> and cache. Are you sure that the SAS RAID Controller is not keeping >>>> everything in the controller cache? >>> This isn't an "SSD". It's connected directly to the PCI Express bus, and >>> "low cost" it certainly is NOT. It's much more valuable than the server >>> it's plugged into. >>> >>> I've run benchmark tests (iometer), and the benchmarks show it's as fast >>> as the mfgr says it should be (~700MB/sec read and write bandwidth, >>> >115,000 IOPS) but it performs quite poorly when I run my app on it. I >>> can't figure out why. >>> >>> Mark > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
