Re: Ext4 slow on links

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On 6/20/12 12:18 AM, Norbert Preining wrote:
> Hi Eric,
> 
> On Di, 19 Jun 2012, Eric Sandeen wrote:
>> blktrace of the actions would show you something interesting as well.
> 
> I tried to understand the output, but didn't get any information
> that tells me something.
> 
> I rebooted into single user mode, started blktrace on sda, then run
> time ls -l /..../dir/with/links/ >/dev/null, stopped the blktrace.
> 
> Then I run blkparse and btt etc to generate a variety of data.

...

> 
> I don't know if that shows anything of interest, but if you need more,
> and want to waste a bit of time looking at the data, I have uploaded
> everything created into
> 	http://www.logic.at/people/preining/BlkParse.tar.gz

Here are the overall stats:

Total (sda):
 Reads Queued:       8,864,   35,456KiB	 Writes Queued:          90,    7,980KiB
 Read Dispatches:    8,864,   35,456KiB	 Write Dispatches:       49,    7,980KiB
 Reads Requeued:         0		 Writes Requeued:         0
 Reads Completed:    8,864,   35,456KiB	 Writes Completed:       59,    7,980KiB
 Read Merges:            0,        0KiB	 Write Merges:           41,      164KiB
 IO unplugs:            81        	 Timer unplugs:           0

so almost all reads, and no read merges; almost 35 megabytes read and every
one was a small 4k IO.

It's doing about 120 seeks/second.  I'm a little surprised that there was no read
merging...

Let me think about this. :)

-Eric
--
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


[Reiser Filesystem Development]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Linux FS]     [Photo]     [Yosemite]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Device Mapper]     [Linux Resources]


  Powered by Linux