[Lustre-discuss] Patchless kernel support?

[Bernd Schubert]

Hi all,

I think Ashley means patchless server support. That is already tracked in 
bug#21524.

Ashley, while patchless server suppoert certainly is a good idea, it might not 
always be as helpful as you believe. Updating the presently existing patches 
is usually rather straight forward. Far more difficult is if the VFS changes 
and new methods and configure checks have to be implemented in Lustre. That 
made it so difficult to update Lustre to 2.6.24 and now again the limit had 
been 2.6.32 (maybe the VFS changes already had been in before, but I didn't 
track linux-git recently that much). And those changes in the VFS are often 
also completely unrelated to kernel patches...

I also planned to work on the sd_io stats. But I think that patch simply 
should be dropped in favour of blktrace. Current blkiomon does almost the same 
as the sd_io stats, but IMHO neither of both approaches is really helpful. So 
I have a modified blkiomon version (not ready for patch submission yet), that 
does similar stats as the DDN S2A controllers and IMHO only those detailed 
stats are really helpful to analyze IO patterns. If it comes to me, neither 
sd_io stats, nor DDN SFA nor upstream blkiomon have sufficiently detailed 
information to see where the problem is.
I understand that blktrace has some overhead compared to sd_io stats. However, 
if sd_io stats is supposed to ever land upstream, it needs to be rewritten 
from procfs to debugfs. I think even sysfs is not suitable for it.

Cheers,
Bernd

On Thursday, November 25, 2010, Alexey Lyashkov wrote:
> Ashley,
> 
> I don't clearry understand what you want, if you say about patchless
> support on client - typical size of adding support of one new kernel to
> pachless client is ~40kb of patch for lustre. Sometimes is has more work,
> sometimes less.
> As last lustre supported kernel is 2.6.32 - you should be plan to have
> ~150kb patch for 2.6.37 kernel support. if you say about patchless kernel
> support - yes, that is possible, but that is need more work and submiting
> lots patches in kernel upstream.
> 
> On Nov 25, 2010, at 15:18, Ashley Pittman wrote:
> > Picking up from something that was said at SC last week I believe it was
> > Andreas that mentioned the possibility of patch-less kernel support. 
> > This is something that would be immensely useful to us for a variety of
> > reasons.
> > 
> > Has there been any recent work into investigating how much work would be
> > involved in implementing this and what's the feeling for if it could be
> > done though changes to Lustre only or a case of submitting a number of
> > patches upstream?
> > 
> > Ashley.
> > _______________________________________________
> > Lustre-discuss mailing list
> > Lustre-discuss at lists.lustre.org
> > http://lists.lustre.org/mailman/listinfo/lustre-discuss
> 
> _______________________________________________
> Lustre-discuss mailing list
> Lustre-discuss at lists.lustre.org
> http://lists.lustre.org/mailman/listinfo/lustre-discuss


-- 
Bernd Schubert
DataDirect Networks