----- Original Message -----
> Hi,
>
> That looks better. Do you get better results with it compared with the
> previous version?
>
> Steve.
>
> On 22/04/15 18:00, Bob Peterson wrote:
> > Hi,
> >
> > This patch changes function gfs2_rgrp_congested so that it only factors
> > in non-zero values into its average round trip time. If the round-trip
> > time is zero for a particular cpu, that cpu has obviously never dealt
> > with bouncing the resource group in question, so factoring in a zero
> > value will only skew the numbers. It also fixes a compile error on
> > some arches related to division.
> >
> > Regards,
> >
> > Bob Peterson
> > Signed-off-by: Bob Peterson <[email protected]>
It's not straightforward because the "preferred rgrps" patch skews the
performance results greatly. However, based on my performance tests, yes,
the numbers do look better. I temporarily commented out that "preferred
rgrps" patch to get a clearer picture. Here are numbers from my testing:
This test consists of 5 nodes all simultaneously doing this 'dd' command:
dd if=/dev/zero of=/mnt/gfs2/`hostname` bs=1M count=100
(after drop_caches)
Stock (nothing disabled):
Run 1
--------
pats 716 MB/s
jets 615 MB/s
bills 669 MB/s
dolphins 605 MB/s
ravens 735 MB/s
--------
Average: 668 MB/s
Stock (plus preferred rgrps disabled): AKA 'c3'
Run 1 Run 2
-------- --------
pats 766 MB/s 675 MB/s
jets 649 MB/s 716 MB/s
bills 790 MB/s 735 MB/s
dolphins 761 MB/s 727 MB/s
ravens 712 MB/s 728 MB/s
-------- --------
Average: 736 MB/s 716 MB/s
Without latest patch (plus preferred rgrps disabled): AKA 'c2'
(In other words, this is the previous patch which was called
"GFS2: Use average srttb value in congestion calculations")
Run 1 Run 2 Run 3
-------- -------- ---------
pats 830 MB/s 688 MB/s 697 MB/s
jets 833 MB/s 622 MB/s 645 MB/s
bills 831 MB/s 796 MB/s 637 MB/s
dolphins 834 MB/s 597 MB/s 690 MB/s
ravens 815 MB/s 731 MB/s 734 MB/s
-------- -------- ---------
Average: 829 MB/s 687 MB/s 681 MB/s
Latest patch (plus preferred rgrps disabled):
Run 1 Run 2 Run 3
-------- -------- ---------
pats 811 MB/s 829 MB/s 652 MB/s
jets 825 MB/s 863 MB/s 702 MB/s
bills 846 MB/s 825 MB/s 710 MB/s
dolphins 845 MB/s 845 MB/s 683 MB/s
ravens 820 MB/s 818 MB/s 682 MB/s
-------- -------- ---------
Average: 829 MB/s 836 MB/s 686 MB/s
Latest patch (nothing disabled):
Run 1 Run 2 Run 3
-------- -------- ---------
pats 834 MB/s 817 MB/s 819 MB/s
jets 837 MB/s 835 MB/s 836 MB/s
bills 841 MB/s 837 MB/s 834 MB/s
dolphins 838 MB/s 851 MB/s 842 MB/s
ravens 795 MB/s 808 MB/s 815 MB/s
-------- -------- ---------
Average: 829 MB/s 830 MB/s 829 MB/s
This test (simultaneous dd) is known to be a worst case scenario,
so I expect it to show the most improvement. For ordinary block
allocations, I don't expect that big of an improvement.
Regards,
Bob Peterson
Red Hat File Systems
