Re: scheduler bigpatch for 2.1.128
Jan Kara (jack@atrey.karlin.mff.cuni.cz)
Mon, 16 Nov 1998 21:59:51 +0100
> On Fri, 13 Nov 1998, Pavel Machek wrote:
>
> > > - adds a SCHED_IDLE class for ultra-low priority
> > > processing (can this be used to lock the system?
> > > can anyone find a place within the kernel where
> > > schedule() is called within a critical region?)
> >
> > ask jack@atrey.karlin.mff.cuni.cz, there are such places in ext2 code.
>
> Thanks Pavel...
>
> So Jack, I take it you have a more exact idea on where
> the culprits are located? <devilish smile>
>
Look for example in ext2/ialloc.c on ext2_new_inode(). This routine holds lock on superblock
and calls some bread()s and so on which can call schedule(). This at least forbids any file
creation on the fs... Or in ext2/balloc.c in ext2_new_block() is another place with sb-lock
held and bread() called. This will prohibit any block allocation... So generally reading
will be always possible but all writes will be stopped and waiting...
Have a nice day. Honza.
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