Messages in this thread | | | From | Dan Williams <> | Date | Mon, 1 May 2017 09:16:51 -0700 | Subject | Re: [PATCH] libnvdimm: rework region badblocks clearing |
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On Mon, May 1, 2017 at 9:12 AM, Kani, Toshimitsu <toshi.kani@hpe.com> wrote: > On Mon, 2017-05-01 at 08:52 -0700, Dan Williams wrote: >> On Mon, May 1, 2017 at 8:43 AM, Dan Williams <dan.j.williams@intel.co >> m> wrote: >> > On Mon, May 1, 2017 at 8:34 AM, Kani, Toshimitsu <toshi.kani@hpe.co >> > m> wrote: >> > > On Sun, 2017-04-30 at 05:39 -0700, Dan Williams wrote: > : >> > > >> > > Hi Dan, >> > > >> > > I was testing the change with CONFIG_DEBUG_ATOMIC_SLEEP set this >> > > time, and hit the following BUG with BTT. This is a separate >> > > issue (not introduced by this patch), but it shows that we have >> > > an issue with the DSM call path as well. >> > >> > Ah, great find, thanks! We don't see this in the unit tests because >> > the nfit_test infrastructure takes no sleeping actions in its >> > simulated DSM path. Outside of converting btt to use sleeping locks >> > I'm not sure I see a path forward. I wonder how bad the performance >> > impact of that would be? Perhaps with opportunistic spinning it >> > won't be so bad, but I don't see another choice. >> >> It's worse than that. Part of the performance optimization of BTT I/O >> was to avoid locking altogether when we could rely on a BTT lane >> percpu, so that would also need to be removed. > > I do not have a good idea either, but I'd rather disable this clearing > in the regular BTT write path than adding sleeping locks to BTT. > Clearing a bad block in the BTT write path is difficult/challenging > since it allocates a new block.
Actually, that may make things easier. Can we teach BTT to track error blocks and clear them before they are reassigned?
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