From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse Date: Thu, 23 Apr 2015 18:59:16 +0100 Subject: [Cluster-devel] [GFS2 PATCH] GFS2: Average in only non-zero round-trip times for congestion stats In-Reply-To: <918499302.5872367.1429807501247.JavaMail.zimbra@redhat.com> References: <1549641874.4770984.1429722009576.JavaMail.zimbra@redhat.com> <5538B62C.4030303@redhat.com> <918499302.5872367.1429807501247.JavaMail.zimbra@redhat.com> Message-ID: <553932F4.3050207@redhat.com> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi, On 23/04/15 17:45, Bob Peterson wrote: > ----- 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 > 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 That looks very encouraging I think, definitely a good step forward. Acked-by: Steven Whitehouse Steve.