Hello Minchan, excellent analysis! On (01/30/15 23:41), Minchan Kim wrote: > Yes, __srcu_read_lock is a little bit heavier but the number of instruction > are not too much difference to make difference 10%. A culprit is > __cond_resched but I don't think, either because our test was CPU intensive > soS I don't think schedule latency affects total bandwidth. > > More cuprit is your data pattern. > It seems you didn't use scramble_buffers=0, zero_buffers in fio so that > fio fills random data pattern so zram bandwidth could be different by > compression/decompression ratio. Completely agree. Shame on me. gotten so used to iozone (iozone uses same data pattern 0xA5, this is +Z option what for), so I didn't even think about data pattern in fio. sorry. > 1) randread > srcu is worse as 0.63% but the difference is really marginal. > > 2) randwrite > srcu is better as 1.24% is better. > > 3) randrw > srcu is better as 2.3% hm, interesting. I'll re-check. > Okay, if you concerns on the data still, how about this? I'm not so upset to lose 0.6234187%. my concerns were about iozone's 10% different (which looks a bit worse). I'll review your patch. Thanks for your effort. > > > > by "data pattern" you mean usage scenario? well, I usually use zram for > > `make -jX', where X=[4..N]. so N concurrent read-write ops scenario. > > What I meant is what data fills I/O buffer, which is really important > to evaluate zram because the compression/decompression speeds relys on it. > I see. I never test it with `make' anyway, only iozone +Z. -ss -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>