Re: [Patch 5/7] synchronous block I/O delays

[Shailabh Nagar <nagar@watson.ibm.com>]

Arjan van de Ven wrote:

> > +static inline void delayacct_blkio(void)
> > +{
> > +	if (unlikely(current->delays && delayacct_on))
> > +		__delayacct_blkio();
> > +}
> >    
>
> why is this unlikely?
>  
delayacct_on is expected to be off most of the time, hence the compound is
unlikely too.

>  
>
> > +	u64 blkio_delay;	/* wait for sync block io completion */
> >    
>
> this misses O_SYNC, msync(), and general throttling.
Hmm, that it does :-(

> I get the feeling this is being measured at the wrong level
> currently.... since the number of entry points that needs measuring at
> the current level is hardly finite...
>  
Will take another look if it can be done elsewhere. Earlier was using 
io_schedule but that isn't
called from everywhere.

--Shailabh
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