I'm doing 1 second samples and the rates are very steady. The reason I ended up at this level of testing was I had done a sustained test for 2 minutes at about 5MB/sec and was seeing over 500MB/sec going to the disk, again sampling at 1-second intervals. I'd be happy to provide detailed output and can even sample more frequently if you like.
from my shorter test I was experimenting looking at some of the XFS data with collectl and recorded this, it if help at all:
segerm@az1-sw-object-0006:~$ collectl --import xfs
waiting for 1 second sample...
#<--XFS Ops--><-----------XFS Logging----------><------Extents------><------DirOps-------><----Trans---><-
# Write Reads Writes WrtKBs NoRoom Force Sleep ExtA BlkA ExtF ExtF Look Cre8 Remv Gdnt Sync Asyn Empt
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 3 768 0 3 3 0 0 0 0 0 0 0 0 3 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 1 256 0 1 1 0 0 0 0 0 0 0 0 1 0 0
38 88 95 24320 0 95 96 54 54 54 54 115 76 76 154 95 473 0
339 776 968 247816 0 968 978 484 484 479 479 1011 675 671 1351 967 4087 0
321 748 929 237806 0 929 935 450 450 453 453 967 645 647 1287 930 3847 0
279 637 810 207360 0 810 811 391 391 390 390 838 559 558 1118 810 3324 0
209 482 610 156160 0 610 610 286 286 289 289 627 417 420 834 610 2451 0
0 0 3 768 0 3 3 0 0 0 0 0 0 0 0 3 0 0
I can say for a fact I was doing about 300 wtrites/sec whcih the write numbers seem to support, though I don't know what the read numbers are measuring. you can also see from the logging data that was 250MB/sec going to disk.
Are there other numbers that are meaningful that you'd like to see? All it takes is adding a couple of print statement as what you're seeing above only took a hour or so to throw to together.
I can collect as much (or little as you like) and actually can save the complete contents of /proc/fs/xfs/stat every second in a file for later playback.
-mark
On Fri, Jun 14, 2013 at 8:17 PM, Nathan Scott <nathans@xxxxxxxxxx> wrote:
Ah, good stuff.
----- Original Message -----
> actually I have since found a decoder ring here -
> http://xfs.org/index.php/Runtime_Stats and have been incorporating a lot of
> the data so I can look at things in real time. I'd still love to know why
For how many seconds? (or fractions thereof?) You may need the level of
> writing 1000 1K files results in 200MB/sec of disk I/O though. clearly
detail that only tracing will provide to explore further, although off the
top of my head I'm not sure exactly which events you should focus on (log,
inode creation, or space allocation at a guess).
cheers.
--
Nathan
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