Re: [PATCH v2 5/5] dax: handle media errors in dax_do_io

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, 2016-04-15 at 11:17 -0700, Dan Williams wrote:
> On Fri, Apr 15, 2016 at 11:06 AM, Jeff Moyer <jmoyer@xxxxxxxxxx> wrote:
> > 
> > Dan Williams <dan.j.williams@xxxxxxxxx> writes:
> > 
> > > > > There's a lot of special casing here, so you might consider
> > > > > adding comments.
> > > > Correct - maybe we should reconsider wrapper-izing this? :)
> > > Another option is just to skip dax_do_io() and this special casing
> > > fallback entirely if errors are present.  I.e. only attempt dax_do_io
> > > when: IS_DAX() && gendisk->bb && bb->count == 0.
> >
> > So, if there's an error anywhere on the device, penalize all I/O (not
> > just writes, and not just on sectors that are bad)?  I'm not sure
> > that's a great plan, either.
> > 
> If errors are rare how much are we actually losing in practice?
> Moreover, we're going to do the full badblocks lookup anyway when we
> call ->direct_access().  If we had that information earlier we can
> avoid this fallback dance.

A system running with DAX may have active data set in NVDIMM lager than RAM
size.  In this case, falling back to non-DAX will allocate page cache for
the data, which will saturate the system with memory pressure.

Thanks,
-Toshi  

--
To unsubscribe from this list: send the line "unsubscribe linux-block" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux RAID]     [Linux SCSI]     [Linux ATA RAID]     [IDE]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Device Mapper]

  Powered by Linux