Date: Fri, 31 Jul 2020 11:44:20 -0400 From: mike tancsa <mike@sentex.net> To: Eugene Grosbein <eugen@grosbein.net>, FreeBSD-STABLE Mailing List <freebsd-stable@freebsd.org> Subject: Re: zfs meta data slowness Message-ID: <306e7adc-10a0-8f1a-d2b7-12d16ba91557@sentex.net> In-Reply-To: <097a63f1-3b25-3916-cdb9-1d4cf0d088fd@grosbein.net> References: <b6d670e6-6e35-a1f7-7daf-76b458f26e30@sentex.net> <1949194763.1.1595250243575@localhost> <975657af-ccac-bbd1-e22b-86270c624226@sentex.net> <9ddce60a-9d91-fa69-0e11-54342cb67890@grosbein.net> <2267c96f-b988-df1e-887b-77dc9b2a3e32@sentex.net> <097a63f1-3b25-3916-cdb9-1d4cf0d088fd@grosbein.net>
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On 7/22/2020 9:26 AM, Eugene Grosbein wrote: > > It's hard to read due to wrapping plus, it is truncated. > Maybe additional flag -d3 or similar will help, combined with dedirection < /dev/null > top.out > so it won't use size of your terminal to wrap/truncate output. > > Also, make sure you invoke top while "zfs" command is running. > Also, procstat -kk for pid of "zfs" command would be useful (but may occur pretty long). > > I suppose it blocks waiting for some kernel lock and procstat would show details. .txt file is attached. I also ran procstat -kk <pid> in a loop for a bit while it was running. In this case the list too just under 5min to run. time /sbin/zfs list -Hp -oname,creation -S creation -t snapshot > /var/log/snapshots.out 2.311u 24.963s 4:55.13 9.2% 71+179k 2706576+26io 0pf+0w Ideally, I would like to bias slightly ARC to hold this meta data a little longer than evict it out of cache so fast. I put in an nvme disk hoping that would help, but it makes no difference or doesnt seem to anyways. ---Mike
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