https://bugzilla.kernel.org/show_bug.cgi?id=71641 --- Comment #2 from Chia-Hung Chang <fredchang.tc@xxxxxxxxx> --- > > How big was the ramdisk? Since all of the blocks are going through > the journal, even if it is on the journal, it requires more commits > and thus more checkpoint operations, which means more updates to the > disk. A bigger journal will help minimize this issue. > > Would you be willing to grab block traces for both the disk and the > external journal device? > > I will add that the workload of "dd if=/dev/zero of=file" is probably > the worst case for data=journal, and if that's really what you are > doing, it's a case of "doctor, doctor, it hurts when I do that". All > file systems modes will have strengths and weaknesses, and your use > case one where I would simply tell people, "don't use that mode". > > If you want to work on improving it, that's great. Gather data, and > if we can figure out an easy way to improve things, great. But I'll > warn you ahead of time this is not necessarily something I view as > "unreasonable", nor is it something that I would consider a high > priority thing to fix. > - Ted I use two sizes of ramdisk, 128MB and 1024MB. With 1024MB journal area, the performance is slight improved. But performance degradation is still significant. I am willing to grab block traces. Please tell me how to get the traces you want. As you can see that the performance degradation of applying data=journal in raid5 is 80%, which makes it hard to use. If I know where the problem is, I will try to improve it. Thanks for your help. -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
