Messages in this thread | | | From | Roger Heflin <> | Date | Fri, 14 Nov 2014 07:20:33 -0600 | Subject | Re: read performance is too low compared to write - /dev/sda1 |
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If you are robocoping small files you will hit other limits.
Best I have seen with small files is around 30 files/second, and that involves multiple copies going on. Remember with a small files there are several reads and writes that need to be done to complete a create of a small file and each of these take time. 30 files/second ~ 30ms per file, not that bad considering that on a real spinning disk a single read/write op is 5-10ms, and creating the file entry, copying data and closing the file takes several operations (at least create file entry, write small amount of data, update file entry date/time/info). If the write in the middle is not a significant amount of data, the 2 extra ops are what hurts.
On Fri, Nov 14, 2014 at 6:55 AM, Jagan Teki <jagannadh.teki@gmail.com> wrote: > Hi, > > I'm doing a performance testing on my bench ARM box. > > 1. dd test: I have validate the read and write by mounting /dev/sda1 > with ext4 filesystem, > able to get the good performance numbers where read is high > compared to write > > 2. robocopy test: > - mkfs.ext4 /dev/sda1 > - mount /dev/sda1 /media/disk > - << configured samba >> > - Mapped the /media/disk on windows > - login on the mapped driver in windows > - did a robocopy test, where write got 84MBps and read 14MBps > > read performance is too slow when compared to write in robocopy case. > Can anyone help me out, how to debug this further. > > thanks! > -- > Jagan. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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