On 7 Apr, Justin Hibbits wrote: > On Fri, Apr 6, 2018 at 10:25 AM, Justin Hibbits <chmeeedalf_at_gmail.com> wrote: >> On Fri, Apr 6, 2018 at 10:08 AM, Mark Johnston <markj_at_freebsd.org> wrote: >>> On Fri, Apr 06, 2018 at 12:47:14AM +0000, Justin Hibbits wrote: >>>> My powerpc64 embedded machine is virtually unusable since these vm changes. >>>> I tried setting vfs.zfs.arc_free_target as suggested, and that didn't help >>>> at all. Eventually the machine hangs and just gets stuck in vmdaemon, with >>>> many processes in wait channel btalloc. >>> >>> You don't really have the same symptoms that Don is reporting. >> >> Okay. I latched onto the thread because it seemed similar. >> >>> Threads being stuck in btalloc implies a KVA shortage. So: >>> - What do you mean by "stuck in vmdaemon"? >> >> The machine hangs, and my ssh sessions get killed. I can't do >> anything at the console except break into kdb. When I do, the running >> thread is always vmdaemon. >> >>> - Which commits specifically cause problems? Does reverting r329882 fix the >>> hang? >> >> I'll try reverting it and report back. Thankfully I can buildkernel >> successfully on the machine before it hangs. Can't do more than that, >> though. > > I reverted back to r329881, and successfully built world. Updated to > r329882 and it got stuck with processes in btalloc. > > I've seen other reports of r329882 causing problems on powerpc64 as > well, with other bizarre behaviors. I initially missed that this was on powerpc. I believe that arch is a bit odd with characters unsigned by default and arithmentic shifts always being unsigned. Things like that could mess up the algorithm, but I didn't see anything suspicious in the r329882 diff.Received on Sat Apr 07 2018 - 17:56:12 UTC
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