On Tue, May 30, 2017 at 04:11:20PM -0400, Benjamin Coddington wrote: > On 30 May 2017, at 15:34, J. Bruce Fields wrote: > > >On Tue, May 30, 2017 at 02:58:00PM -0400, Chuck Lever wrote: > >>Hey Bruce! > >> > >>While testing with sec=krb5 and sec=krb5i, I noticed a lot of > >>spurious connection loss, especially when I wanted to run a > >>CPU-intensive workload on my NFS server at the same time I > >>was testing. > >> > >>I added a pr_err() in gss_check_seq_num, and ran a fio job > >>on a vers=3,sec=sys,proto=tcp mount (server is exporting a > >>tmpfs). On the server, I rebuilt a kernel source tree cscope > >>database at the same time. > >> > >>May 29 17:53:13 klimt kernel: gss_check_seq_num: seq_num = > >>250098, sd_max = 250291, GSS_SEQ_WIN = 128 > >>May 29 17:53:33 klimt kernel: gss_check_seq_num: seq_num = > >>937816, sd_max = 938171, GSS_SEQ_WIN = 128 > >>May 29 17:53:33 klimt kernel: gss_check_seq_num: seq_num = > >>938544, sd_max = 938727, GSS_SEQ_WIN = 128 > >>May 29 17:53:33 klimt kernel: gss_check_seq_num: seq_num = > >>938543, sd_max = 938727, GSS_SEQ_WIN = 128 > >>May 29 17:53:34 klimt kernel: gss_check_seq_num: seq_num = > >>939344, sd_max = 939549, GSS_SEQ_WIN = 128 > >>May 29 17:53:35 klimt kernel: gss_check_seq_num: seq_num = > >>965007, sd_max = 965176, GSS_SEQ_WIN = 128 > >>May 29 17:54:01 klimt kernel: gss_check_seq_num: seq_num = > >>1799710, sd_max = 1799982, GSS_SEQ_WIN = 128 > >>May 29 17:54:02 klimt kernel: gss_check_seq_num: seq_num = > >>1831165, sd_max = 1831353, GSS_SEQ_WIN = 128 > >>May 29 17:54:04 klimt kernel: gss_check_seq_num: seq_num = > >>1883583, sd_max = 1883761, GSS_SEQ_WIN = 128 > >>May 29 17:54:07 klimt kernel: gss_check_seq_num: seq_num = > >>1959316, sd_max = 1959447, GSS_SEQ_WIN = 128 > >> > >>RFC 2203 suggests there's no risk to using a large window. > >>My first thought was to make the sequence window larger > >>(say 2048) but I've seen stragglers outside even that large > >>a window. > >> > >>Any thoughts about why there are these sequence number > >>outliers? > > > >No, alas. > > I noticed some slow allocations on the server with krb5 last year - but > never got around to doing anything about it: > http://marc.info/?t=146032122900006&r=1&w=2 > > Could be the same thing? I don't think it would be too hard to eliminate the need for allocations there. Or maybe there's even a quick hack that would let Chuck test whether that's the problem (different GFP flags on those allocations?) --b. -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
