Hi, Alan It should be no changes on the system. I compared the per io dump info, and found the merges did decrease a lot. Another interesting thing I found from the blkparse output is the write requests has much more "WS" (synchronous) flag in the replay run. Does the merges decrease due to the "S" flag? Perhaps I need to tune the "-max-pkts"? In my case, to increase its value to let more requests have more opportunities to merge? BTW. I also tried replaying "dd" traces, and found the number of merges also decreases. Thx, Xuekun On Wed, Mar 3, 2010 at 10:05 PM, Alan D. Brunelle <Alan.Brunelle@xxxxxx> wrote: > > Hi Xuekun - > > Not sure why they Q2Q N value is down 5%, but the AVG Q2Q is pretty > close - only 11msec (again, about 5%). After that, things are affected > by merge rates most likely - note that there were 262882 merges on the > first run whilst there were only 8970 on the second run. Perhaps you > could look at the blkparse output from both and get a feel for the vast > reduction in merges. [Any changes on the system between the runs?] > > Regards, > Alan > > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrace" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
