Re: An issue with fio performance on an SSD
|[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]|
Vivek Goyal wrote:
On Mon, Jul 19, 2010 at 01:25:06PM -0400, Joe Landman wrote:Joe Landman wrote:Greetings We are playing with some SSDs, and as usual, we want to use fio for our testing regime. So we set up a simple streaming write:Ok, I figured it out. Add zero_buffers=1 to the job specification. Then we get this: Run status group 0 (all jobs): WRITE: io=32,706MB, aggrb=535MB/s, minb=548MB/s, maxb=548MB/s, mint=61133msec, maxt=61133msecInteresting. Why not initializing bufferes with zero leads to poor performance?
I think this is an SSD controller compression issue. That is, the Sandforce controllers want to do compression of some sort on the data. So if we start out with truly random data, which doesn't get good compression ratios, we get not so good performance.
Joe -- Joseph Landman, Ph.D Founder and CEO Scalable Informatics Inc. email: landman@xxxxxxxxxxxxxxxxxxxxxxx web : http://scalableinformatics.com http://scalableinformatics.com/jackrabbit phone: +1 734 786 8423 x121 fax : +1 866 888 3112 cell : +1 734 612 4615 -- To unsubscribe from this list: send the line "unsubscribe fio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html