Re: kern/39206: ffs um_lock handling isn't great

[Antti Kantee <pooka%cs.hut.fi@localhost>]

The following reply was made to PR kern/39206; it has been noted by GNATS.

From: Antti Kantee <pooka%cs.hut.fi@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/39206: ffs um_lock handling isn't great
Date: Sun, 27 Jul 2008 18:43:41 +0300

 On Fri Jul 25 2008 at 14:15:00 +0000, Simon Burge wrote:
 >         Code inspection.  Pooka suggested introducing a sleep after
 >         um_lock is dropped at the top of ffs_alloccg() and have more
 >         than one thread trying to allocate blocks in the filesystem.
 
 Just wanted to state the obvious in case someone wants to try to prove
 this is a problem: the threads need to want to allocate a block from the
 same cylinder group, which must have room to satisfy only one allocation.