[linux-lvm] Performance problem.
spam at tnonline.net
Mon Nov 17 12:24:01 UTC 2003
>> Actually. SMB never gives optimal transfer speeds. On a HUB you
>> can expect not much more than 6-7MB/S on a 100mbit connection.
>> With a Switch you can get higher, up to 12.5MB/s over FTP (but
>> never with SMB due to protocol overhead etc).
> yeah, I thought it was smb at first aswell, but I get the exact
> same speed over ftp. And rm'ing a file (on ssh to the server) and
> playing a mp3 at the same time shouldn't make the mp3 skip 1-3
> seconds should it?
No, that is true. Your low read speed does indicate that you are
not using DMA. Give us the output of "hdparm /dev/hda". Also a
simple benchmark is to do "dd_rescue /dev/hda /dev/null". What does
that give you in numbers?
> And I've had a stable 11mb/sec out of smb before (tweaked).
>> Also there is this tool called elvtune. It allowes you to "tune the I/O
>> elevator per blockdevice queue basis". See the man pages.
>> You could try to lower the read latency for the affected devices (/dev/hda,
>> /dev/hdb, etc.)
> elvtune shows read_latency of 2048 and write_latency of 8192,
> that's already quite low isn't it? If not, have any example values
> I can test with?
> cat .config | grep -i tcq shows
> # CONFIG_BLK_DEV_IDE_TCQ is not set
> should I manually set it and compile? It's not in make_config.
You can try. Though I suspect you will not gain much speed.
> also does anyone have a lvmcreate_initrd script for lvm2?
> just did a bonnie++ test on the lvm volume. Seems VERY slow doesen't it.
> Version 1.03 ------Sequential Output------ --Sequential Input- --Random-
> -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
> Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
> hollowtube 1G 3787 93 26948 62 10841 14 5885 90 21274 17 175.3 1
> ------Sequential Create------ --------Random Create--------
> -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
> files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
> 16 4991 98 +++++ +++ 4135 90 4613 91 +++++ +++ 3912 89
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