From: Christoph Hellwig <hch@lst.de>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
Keith Busch <keith.busch@intel.com>,
linux-rdma@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-block@vger.kernel.org
Subject: Re: [PATCH v2 6/6] nvme-multipath: disable polling for underlying namespace request queue
Date: Thu, 13 Dec 2018 16:52:35 +0100 [thread overview]
Message-ID: <20181213155235.GA10566@lst.de> (raw)
In-Reply-To: <4f3f213e-9042-5963-d47d-0ee501bf94fa@grimberg.me>
On Thu, Dec 13, 2018 at 07:49:42AM -0800, Sagi Grimberg wrote:
>
>> + if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
>> + bio->bi_opf &= ~REQ_HIPRI;
>> +
>
> Maybe we can simply check (q->queue_flags & (1 << QUEUE_FLAG_POLL)) and
> avoid the extra atomic operation in the host path?
>
> Would it make sense?
test_bit is not usually implemented as an atomic operation.
Take a look at e.g.
arch/x86/include/asm/bitops.h:constant_test_bit()
WARNING: multiple messages have this Message-ID (diff)
From: hch@lst.de (Christoph Hellwig)
Subject: [PATCH v2 6/6] nvme-multipath: disable polling for underlying namespace request queue
Date: Thu, 13 Dec 2018 16:52:35 +0100 [thread overview]
Message-ID: <20181213155235.GA10566@lst.de> (raw)
In-Reply-To: <4f3f213e-9042-5963-d47d-0ee501bf94fa@grimberg.me>
On Thu, Dec 13, 2018@07:49:42AM -0800, Sagi Grimberg wrote:
>
>> + if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
>> + bio->bi_opf &= ~REQ_HIPRI;
>> +
>
> Maybe we can simply check (q->queue_flags & (1 << QUEUE_FLAG_POLL)) and
> avoid the extra atomic operation in the host path?
>
> Would it make sense?
test_bit is not usually implemented as an atomic operation.
Take a look at e.g.
arch/x86/include/asm/bitops.h:constant_test_bit()
next prev parent reply other threads:[~2018-12-13 15:52 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-13 6:38 [PATCH v2 0/6] restore nvme-rdma polling Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 6:38 ` [PATCH v2 1/6] block: introduce blk_execute_rq_polled Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 8:24 ` Christoph Hellwig
2018-12-13 8:24 ` Christoph Hellwig
2018-12-13 15:23 ` Steve Wise
2018-12-13 15:23 ` Steve Wise
2018-12-13 6:38 ` [PATCH v2 2/6] nvme-core: allow __nvme_submit_sync_cmd to poll Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 8:27 ` Christoph Hellwig
2018-12-13 8:27 ` Christoph Hellwig
2018-12-13 15:19 ` Steve Wise
2018-12-13 15:19 ` Steve Wise
2018-12-13 6:38 ` [PATCH v2 3/6] nvme-fabrics: allow nvmf_connect_io_queue " Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 8:27 ` Christoph Hellwig
2018-12-13 8:27 ` Christoph Hellwig
2018-12-13 15:25 ` Steve Wise
2018-12-13 15:25 ` Steve Wise
2018-12-13 6:38 ` [PATCH v2 4/6] nvme-fabrics: allow user to pass in nr_poll_queues Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 15:26 ` Steve Wise
2018-12-13 15:26 ` Steve Wise
2018-12-13 6:38 ` [PATCH v2 5/6] nvme-rdma: implement polling queue map Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 15:28 ` Steve Wise
2018-12-13 15:28 ` Steve Wise
2018-12-13 6:38 ` [PATCH v2 6/6] nvme-multipath: disable polling for underlying namespace request queue Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 8:31 ` Christoph Hellwig
2018-12-13 8:31 ` Christoph Hellwig
2018-12-13 15:49 ` Sagi Grimberg
2018-12-13 15:49 ` Sagi Grimberg
2018-12-13 15:52 ` Christoph Hellwig [this message]
2018-12-13 15:52 ` Christoph Hellwig
2018-12-13 16:14 ` Sagi Grimberg
2018-12-13 16:14 ` Sagi Grimberg
2018-12-13 20:13 ` Christoph Hellwig
2018-12-13 20:13 ` Christoph Hellwig
2018-12-13 15:28 ` Steve Wise
2018-12-13 15:28 ` Steve Wise
2018-12-13 6:38 ` [PATCH v2 nvme-cli 7/6] fabrics: pass in number of polling queues Sagi Grimberg
2018-12-13 6:38 ` Sagi Grimberg
2018-12-13 15:29 ` Steve Wise
2018-12-13 15:29 ` Steve Wise
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