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Date: Fri, 14 Nov 2014 07:52:59 -0600 From: Roger Heflin <rogerheflin@...il.com> To: Jagan Teki <jagannadh.teki@...il.com> Cc: Tejun Heo <tj@...nel.org>, davem <davem@...emloft.net>, linux-ide <linux-ide@...r.kernel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: read performance is too low compared to write - /dev/sda1 What kind of underlying disk is it? On Fri, Nov 14, 2014 at 7:36 AM, Jagan Teki <jagannadh.teki@...il.com> wrote: > On 14 November 2014 18:50, Roger Heflin <rogerheflin@...il.com> wrote: >> 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. >> > > But, I tried 4gb and 1gb files both got a similar numbers. > >> On Fri, Nov 14, 2014 at 6:55 AM, Jagan Teki <jagannadh.teki@...il.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@...r.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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