On 17/02/2020 20:58, Sarah Newman wrote: > On 1/7/20 6:25 AM, Alastair Browne wrote: >> >> CONCLUSION >> >> So in conclusion, the tests indicate that credit2 might be unstable. >> >> For the time being, we are using credit as the chosen scheduler. We >> are booting the kernel with a parameter "sched=credit" to ensure that >> the correct scheduler is used. >> >> After the tests, we decided to stick with 4.9.0.9 kernel and 4.12 Xen >> for production use running credit1 as the default scheduler. > > One person CC'ed appears to be having the same experience, where the credit2 > scheduler leads to lockups (in this case in the domU, not the dom0) under > relatively heavy load. It seems possible they may have the same root cause. > > I don't think there are, but have there been any patches since the 4.13.0 > release which might have fixed problems with credit 2 scheduler? If not, > what would the next step be to isolating the problem - a debug build of Xen > or something else? > > If there are no merged or proposed fixes soon, it may be worth considering > making the credit scheduler the default again until problems with the > credit2 scheduler are resolved. > > Thanks, Sarah > >
Hi Sarah / Alastair, I can only provide my n=1 (OK, I'm running a bunch of boxes, some of which pretty over-committed CPU wise), but I haven't seen any issues (lately) with credit2. I did take a look at Alastair Browne's report your replied to (https://lists.xen.org/archives/html/xen-devel/2020-01/msg00361.html) and I do see some differences: - Alastair's machine has multiple sockets, my machines don't. - It seems Alastair's config is using ballooning ? (dom0_mem=4096M,max:16384M), for me that has been a source of trouble in the past, so my configs don't. - kernel's tested are quite old (4.19.67 (latest upstream is 4.19.104), 4.9.189 (latest upstream is 4.9.214)) and no really new kernel is tested (5.4 is available in Debian backport for buster). - Alastair, are you using pv, hvm or pvh guests? The report seems to miss the Guest configs (I'm primarily using PVH, and few HVM's, no PV except for dom0) ? Any how, could be worthwhile to test without ballooning, and test a recent kernel to rule out an issue with (missing) kernel backports. -- Sander _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
