From: Hannes Reinecke <hare@suse.de>
To: Mike Christie <michaelc@cs.wisc.edu>,
Bart Van Assche <bvanassche@acm.org>
Cc: Sean Stewart <sean.stewart@netapp.com>,
Martin George <marting@netapp.com>,
linux-scsi@vger.kernel.org
Subject: Re: [PATCH 04/16] scsi_dh_alua: Make stpg synchronous
Date: Wed, 19 Feb 2014 09:09:29 +0100 [thread overview]
Message-ID: <530466B9.3060903@suse.de> (raw)
In-Reply-To: <52FE5EA5.3020905@cs.wisc.edu>
On 02/14/2014 07:21 PM, Mike Christie wrote:
> On 2/14/14 5:37 AM, Bart Van Assche wrote:
[ .. ]
>> I think this will only be sufficient if there are more CPU threads
>> available than the number of LUNs for which an STPG has to be issued.
>
> Ah shoot, you reminded me of some other issue. With the above
> command we only can do 1 unit of work at a time. With the
> alloc_workqueue example I sent in the other mail, I think it would
> create a new problem.
>
> alloc_workqueue with max_active=0 looks like it has the wq code
> dynamically create worker threads as needed, so with that we could
> end up with a lot of threads and can failover lots of devices (512
> with the current max) in parallel. The threads will even get reaped
> when they are not needed. However, trying to create lots of threads
> at failover time might have issues, and in general creating 32 or 64
> threads or more is probably not something we want to do.
Another followup: Mike is, as usual, right.
I need to use 'alloc_workqueue' to be able to have more than one
worker at a time.
And also Bart is right in that it makes sense to have STPG run
asynchronously.
However, in doing so I'll be bunching together STPG activations from
several request_queues, and will be deferring I/O on those
queues during STPG update.
So to avoid stalled I/O I'll need to kick each of the queues again
after STPG is finished, right?
Hmm. Let's see how this will look like.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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next prev parent reply other threads:[~2014-02-19 8:09 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-31 9:29 [PATCHv2 00/16] scsi_dh_alua updates Hannes Reinecke
2014-01-31 9:29 ` [PATCH 01/16] scsi_dh_alua: Improve error handling Hannes Reinecke
2014-02-14 11:16 ` Bart Van Assche
2014-02-14 11:32 ` Hannes Reinecke
2014-03-06 23:43 ` Jeremy Linton
2014-03-07 7:12 ` Hannes Reinecke
2014-03-07 15:46 ` Jeremy Linton
2014-01-31 9:29 ` [PATCH 02/16] scsi_dh_alua: use flag for RTPG extended header Hannes Reinecke
2014-01-31 9:29 ` [PATCH 03/16] scsi_dh_alua: Pass buffer as function argument Hannes Reinecke
2014-02-14 11:22 ` Bart Van Assche
2014-02-14 11:36 ` Hannes Reinecke
2014-01-31 9:29 ` [PATCH 04/16] scsi_dh_alua: Make stpg synchronous Hannes Reinecke
2014-02-07 1:24 ` Mike Christie
2014-02-07 1:54 ` Mike Christie
2014-02-12 15:29 ` Hannes Reinecke
2014-02-12 16:11 ` Mike Christie
2014-02-12 16:26 ` Mike Christie
2014-02-12 17:31 ` Mike Christie
2014-02-13 9:31 ` Hannes Reinecke
2014-02-14 11:37 ` Bart Van Assche
2014-02-14 11:53 ` Hannes Reinecke
2014-02-14 18:21 ` Mike Christie
2014-02-19 8:09 ` Hannes Reinecke [this message]
2014-02-14 17:17 ` Mike Christie
2014-02-14 11:27 ` Bart Van Assche
2014-02-14 11:38 ` Hannes Reinecke
2014-01-31 9:29 ` [PATCH 05/16] scsi_dh_alua: put sense buffer on stack Hannes Reinecke
2014-01-31 9:29 ` [PATCH 06/16] scsi_dh_alua: use local buffer for VPD inquiry Hannes Reinecke
2014-02-13 9:51 ` Maurizio Lombardi
2014-02-13 10:10 ` Hannes Reinecke
2014-02-14 11:41 ` Bart Van Assche
2014-01-31 9:29 ` [PATCH 07/16] scsi_dh_alua: Use separate alua_port_group structure Hannes Reinecke
2014-02-14 11:56 ` Bart Van Assche
2014-02-14 12:16 ` Hannes Reinecke
2014-02-14 16:12 ` Hannes Reinecke
2014-02-14 17:42 ` Bart Van Assche
2014-01-31 9:29 ` [PATCH 08/16] scsi_dh_alua: parse target device id Hannes Reinecke
2014-02-14 12:09 ` Bart Van Assche
2014-02-14 12:21 ` Hannes Reinecke
2014-02-17 14:05 ` Bart Van Assche
2014-02-17 14:09 ` Hannes Reinecke
2014-02-17 14:27 ` Bart Van Assche
2014-02-17 14:33 ` Hannes Reinecke
2014-02-18 7:26 ` Bart Van Assche
2014-01-31 9:29 ` [PATCH 09/16] scsi_dh_alua: simplify sense code handling Hannes Reinecke
2014-01-31 9:29 ` [PATCH 10/16] scsi_dh_alua: Do not attach to management devices Hannes Reinecke
2014-01-31 9:29 ` [PATCH 11/16] scsi_dh_alua: multipath failover fails with error 15 Hannes Reinecke
2015-03-30 12:30 ` Bart Van Assche
2015-03-30 12:32 ` Hannes Reinecke
2014-01-31 9:29 ` [PATCH 12/16] scsi_dh: return individual errors in scsi_dh_activate() Hannes Reinecke
2014-01-31 9:29 ` [PATCH 13/16] scsi_dh_alua: Clarify logging message Hannes Reinecke
2014-01-31 9:29 ` [PATCH 14/16] scsi_dh: invoke callback if ->activate is not present Hannes Reinecke
2014-01-31 9:29 ` [PATCH 15/16] scsi_dh_alua: revert commit a8e5a2d593cbfccf530c3382c2c328d2edaa7b66 Hannes Reinecke
2014-01-31 9:30 ` [PATCH 16/16] scsi_dh_alua: Use workqueue for RTPG Hannes Reinecke
2014-02-14 19:03 ` Bart Van Assche
2014-04-29 21:47 ` Stewart, Sean
2014-05-08 7:04 ` Hannes Reinecke
2014-03-02 9:10 ` [PATCHv2 00/16] scsi_dh_alua updates Bart Van Assche
-- strict thread matches above, loose matches on Subject: below --
2013-12-20 12:13 [PATCH " Hannes Reinecke
2013-12-20 12:13 ` [PATCH 04/16] scsi_dh_alua: Make stpg synchronous Hannes Reinecke
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