On 15 September 2017 at 11:54, Michał Sokołowski <mic...@sarach.com.pl> wrote: [..] >> Just please some example which I can try to replay which ill be >> showing that we have similar results. > > Case #1 > 2x 7200 rpm HDD -> md raid 1 -> host BTRFS rootfs -> qemu cow2 storage > -> guest BTRFS filesystem > SQL table row insertions per second: 1-2 > > Case #2 > 2x 7200 rpm HDD -> md raid 1 -> host BTRFS rootfs -> qemu raw storage -> > guest EXT4 filesystem > SQL table row insertions per second: 10-15
Q -1) why you are comparing btrfs against ext4 on top of the btrfs which is doing own COW operations on bottom of such sandwiches .. if we SUPPOSE to be talking about impact of the fragmentation on top of btrfs? Q 0) what do you think that you measure here? Q 1) how did you produce those time measurements? time command? looking on the watch? Q 2) why there are ranges of timings? did you repeat some operations few times (how many times and with or without dropping caches or doing reboots?) Q 3) What kind of SQL engine? with what kind of settings? with what kind of tables? (indexes? foreign keys?) What kind of transactions semantics? Q 4) where is the example set of inserts which I can replay in my setup? did you drop caches before batch of inserts? (do you know that every insert generates as well some number of read IOs so information is something is already cached before batch of inserts is *crucial*) Did you restart SQL engine? Q 5) are both test have been executed on the same box? if not which one version of the kernel(s) have been used? Q 6) ) effectively how many IOs have been done during those tests? how did you measured those numbers (dtrace? perf? systemtap?) Q7) why you are running your tests over qemu? Is it anything more running on the host system during those tests? . . . I can probably make this list of questions 2 or 3 times longer. koczek -- Tomasz Kłoczko | LinkedIn: http://lnkd.in/FXPWxH -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
