Re: scsi-mq V2

[Jeff Moyer <jmoyer@redhat.com>]

"Elliott, Robert (Server Storage)" <Elliott@hp.com> writes:

>> -----Original Message-----
>> From: Christoph Hellwig [mailto:hch@infradead.org]
>> Sent: Thursday, 10 July, 2014 11:15 AM
>> To: Elliott, Robert (Server Storage)
>> Cc: Jens Axboe; dgilbert@interlog.com; James Bottomley; Bart Van Assche;
>> Benjamin LaHaise; linux-scsi@vger.kernel.org; linux-kernel@vger.kernel.org
>> Subject: Re: scsi-mq V2
>> 
>> On Thu, Jul 10, 2014 at 09:04:22AM -0700, Christoph Hellwig wrote:
>> > It's starting to look weird.  I'll prepare another two bisect branches
>> > around some MM changes, which seems the only other possible candidate.
>> 
>> I've pushed out scsi-mq.3-bisect-3 
>
> Good.
>
>> and scsi-mq.3-bisect-4 for you.
>
> Bad.
>
> Note: I had to apply the vdso2c.h patch to build this -rc3 based kernel:
> diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h
> index df95a2f..11b65d4 100644
> --- a/arch/x86/vdso/vdso2c.h
> +++ b/arch/x86/vdso/vdso2c.h
> @@ -93,6 +93,9 @@ static void BITSFUNC(copy_section)(struct BITSFUNC(fake_sections) *out,
> 	uint64_t flags = GET_LE(&in->sh_flags);
>
> 	bool copy = flags & SHF_ALLOC &&
> +		(GET_LE(&in->sh_size) ||
> +		(GET_LE(&in->sh_type) != SHT_RELA &&
> +		GET_LE(&in->sh_type) != SHT_REL)) &&
> 		strcmp(name, ".altinstructions") &&
> 		strcmp(name, ".altinstr_replacement");
>
> Results: fio started OK, getting 900K IOPS, but ^C led to 0 IOPS and
> an fio hang, with one CPU (CPU 0) stuck in io_submit loops.

Hi, Rob,

Can you get sysrq-t output for me?  I don't know how/why we'd continue
to get io_submits for an exiting process.

Thanks,
Jeff