Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 12 Jan 2021 09:35:34 -0800 | Subject | Re: kernel BUG at mm/page-writeback.c:LINE! |
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On Tue, Jan 12, 2021 at 2:44 AM Jan Kara <jack@suse.cz> wrote: > > On Fri 08-01-21 18:04:21, Linus Torvalds wrote: > > > > Oh, and Michael Larabel (of phoronix) reports that that one-liner does > > something bad to a few PostgreSQL tests, on the order of 5-10% > > regression on some machines (but apparently not others). > > Do you have more details? From my experience (we do regular pgbench runs > for various kernels in various configs in SUSE) PostgreSQL numbers tend to > be somewhat noisy and more dependent on CPU scheduling and NUMA locality > than anything else. But it very much depends on the exact config passed to > pgbench so that's why I'm asking...
No, I don't really have many more details. I don't have things like raw numbers or exact configurations, but Michael has been very responsive if you ask, so if you are interested, just email him at Michael Larabel <Michael@michaellarabel.com>.
It wasn't NUMA - apparently the machines he saw this on were just plain consumer setups, and his larger machines didn't actually show the effect. But yes, I suspect it was some scheduling artifact, and probably just fairly random noise from just changing the scheduling pattern a bit.
Linus
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