Re: [PATCH V5 13/14] block: mq-deadline: Limit write request dispatch for zoned block devices

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, 2017-09-25 at 22:06 +0000, Bart Van Assche wrote:
> On Mon, 2017-09-25 at 15:14 +0900, Damien Le Moal wrote:
> > -	return rq_entry_fifo(dd->fifo_list[data_dir].next);
> > +	if (!dd->zones_wlock || data_dir == READ)
> > +		return rq_entry_fifo(dd->fifo_list[data_dir].next);
> > +
> > +	spin_lock_irqsave(&dd->zone_lock, flags);
> > +
> > +	list_for_each_entry(rq, &dd->fifo_list[WRITE], queuelist) {
> > +		if (deadline_can_dispatch_request(dd, rq))
> > +			goto out;
> > +	}
> > +	rq = NULL;
> > +
> > +out:
> > +	spin_unlock_irqrestore(&dd->zone_lock, flags);
> 
> Is it documented somewhere what dd->zone_lock protects and when that lock
> should be
> acquired?

It was not well explained. I added comments in V6.

> 
> > 	/*
> >  	 * This may be a requeue of a request that has locked its
> > -	 * target zone. If this is the case, release the request zone
> > lock.
> > +	 * target zone. If this is the case, release the zone lock.
> >  	 */
> >  	if (deadline_request_has_zone_wlock(rq))
> >  		deadline_wunlock_zone(dd, rq);
> 
> Can this change be folded into the patch that introduced that comment?

Of course. Fixed in V6.

> > @@ -570,6 +621,9 @@ static void dd_insert_request(struct blk_mq_hw_ctx
> > *hctx, struct request *rq,
> >  
> >  	blk_mq_sched_request_inserted(rq);
> >  
> > +	if (at_head && deadline_request_needs_zone_wlock(dd, rq))
> > +		pr_info("######## Write at head !\n");
> > +
> >  	if (at_head || blk_rq_is_passthrough(rq)) {
> >  		if (at_head)
> >  			list_add(&rq->queuelist, &dd->dispatch);
> 
> Will it be easy to users who analyze a kernel log to figure out why that
> message has been generated? Should that message perhaps include the block
> device name, zone number and request sector number?

This was just a debug message for me that I forgot to remove. I did in V6.
Thanks for catching this.

Best regards.

-- 
Damien Le Moal
Western Digital




[Index of Archives]     [Linux RAID]     [Linux SCSI]     [Linux ATA RAID]     [IDE]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Device Mapper]

  Powered by Linux