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From: "jianchao.wang" <jianchao.w.wang@oracle.com>
To: Bart Van Assche <Bart.VanAssche@wdc.com>, "hch@lst.de" <hch@lst.de>
Cc: "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"israelr@mellanox.com" <israelr@mellanox.com>,
	"sagi@grimberg.me" <sagi@grimberg.me>,
	"sebott@linux.ibm.com" <sebott@linux.ibm.com>,
	"ming.lei@redhat.com" <ming.lei@redhat.com>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"maxg@mellanox.com" <maxg@mellanox.com>,
	"tj@kernel.org" <tj@kernel.org>
Subject: Re: [PATCH] blk-mq: Rework blk-mq timeout handling again
Date: Mon, 14 May 2018 13:15:57 +0800	[thread overview]
Message-ID: <b7f45d6b-f2a2-a778-9b58-245ecb99e4d9@oracle.com> (raw)
In-Reply-To: <4f773949c3e32a9d65ab09159fb7b6988349e91b.camel@wdc.com>

Hi Bart

On 05/14/2018 12:03 PM, Bart Van Assche wrote:
> On Mon, 2018-05-14 at 09:37 +0800, jianchao.wang wrote:
>> In addition, on a 64bit system, how do you set up the timer with a 32bit deadline ?
> 
> If timeout handling occurs less than (1 << 31) / HZ seconds after a request has been
> submitted then a 32-bit variable is sufficient to store the deadline. If you want to
> verify the implementation, please have a look at the int32_t variables in
> blk_mq_check_expired().
> 
a 32bit deadline is indeed OK to judge whether a request is timeout or not.
but how is the expires value determined for __blk_add_timer -> mod_timer ?
as we know, when a request is started, we need to arm a timer for it.
the expires value is 'unsigned long'.

Thanks
Jianchao 

  reply	other threads:[~2018-05-14  5:15 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-10 17:56 [PATCH] blk-mq: Rework blk-mq timeout handling again Bart Van Assche
2018-05-11 12:06 ` jianchao.wang
2018-05-11 12:35   ` Christoph Hellwig
2018-05-11 15:29     ` Bart Van Assche
2018-05-14  1:37       ` jianchao.wang
2018-05-14  4:03         ` Bart Van Assche
2018-05-14  5:15           ` jianchao.wang [this message]
2018-05-14 18:44             ` Bart Van Assche
2018-05-11 15:26   ` Bart Van Assche
2018-05-14  1:48     ` jianchao.wang

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