Jens Axboe <[email protected]> writes: > On 07/20/2015 01:17 PM, Jeff Moyer wrote: >> >> <resent with Jens' email address fixed> >> >> Hi, >> >> This reverts commit 34b48db66e08, which caused significant iozone >> performance regressions and uncovered a silent data corruption >> bug in at least one disk. >> >> For SAN storage, we've seen initial write and re-write performance drop >> 25-50% across all I/O sizes. On locally attached storage, we've seen >> regressions of 40% for all I/O types, but only for I/O sizes larger than >> 1MB. > > Do we have any understanding of where this regression is coming from? > Even just basic info like iostats from a run would be useful.
I'll request this information and get back to you. Sorry, I should have done more digging first, but this seemed somewhat urgent to me. >> In addition to the performance issues, we've also seen data corruption >> on one disk/hba combination. See >> http://marc.info/?l=linux-ide&m=143680539400526&w=2 > > That's just sucky hardware... That said, it is indeed one of the > risks. We had basically the same transition from 255 as max sectors, > since we depended on ATA treating 0 == 256 sectors (as per spec). Sure, the hardware sucks. I still don't like foisting silent data corruption on users. Besides, given that this patch went in without any performance numbers attached, I'd say the risk/reward ratio right now is in favor of the revert. Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
