lkml.org 
[lkml]   [2004]   [Nov]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] Real-Time Preemption, -RT-2.6.10-rc1-mm3-V0.7.23

* Karsten Wiese <annabellesgarden@yahoo.de> wrote:

> Yes, it always happens, when callling ./cvscompile script of a
> project, that is mounted via nfs. Haven't tried to do that
> ./cvscompile locally, should I?

very interesting, nfs is indeed one of the frequent BKL users.

a 'BKL leak' is an unbalanced lock, e.g.:

lock_kernel();
... do stuff ...
if (error)
return;
... do more stuff ...
unlock_kernel();

the BKL is a very special type of lock which fact has the side-effect
that in the stock kernel a 'BKL leak' can go unnoticed very easily: it
causes no problems other than hard-to-debug (but severe) scalability
regressions. The moment the BKL count leaked from the NFS code that
process has been 'scalability-poisoned' and will be handicapped until it
exits.

In the PREEMPT_RT patchset i added a strict locking checker to do_exit()
that found this apparent NFS bug. Unfortunately the deadlock detector
only reported a pretty common place where the BKL gets
dropped/reacquired frequently so we dont know where the NFS code has the
lock/unlock imbalance. Could you report this bug to the NFS maintainers
(along with the above and the previous analysis)?

Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:07    [W:0.530 / U:1.376 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site