From: Sagi Grimberg <sagi@grimberg.me>
To: Logan Gunthorpe <logang@deltatee.com>,
linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org
Cc: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>,
Stephen Bates <sbates@raithlin.com>, Jens Axboe <axboe@fb.com>,
Keith Busch <kbusch@kernel.org>, Max Gurtovoy <maxg@mellanox.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v8 13/13] nvmet-passthru: support block accounting
Date: Mon, 9 Sep 2019 16:15:25 -0700 [thread overview]
Message-ID: <ca811aea-c4ae-10ee-15a5-2332d5a9e29a@grimberg.me> (raw)
In-Reply-To: <b23c72b2-c9db-cb8e-5519-63eb195b7fd4@deltatee.com>
>>>>> Support block disk accounting by setting the RQF_IO_STAT flag
>>>>> and gendisk in the request.
>>>>>
>>>>> After this change, IO counts will be reflected correctly in
>>>>> /proc/diskstats for drives being used by passthru.
>>>>>
>>>>> Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
>>>>> ---
>>>>> drivers/nvme/target/io-cmd-passthru.c | 5 ++++-
>>>>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/nvme/target/io-cmd-passthru.c b/drivers/nvme/target/io-cmd-passthru.c
>>>>> index 7557927a3451..63f12750a80d 100644
>>>>> --- a/drivers/nvme/target/io-cmd-passthru.c
>>>>> +++ b/drivers/nvme/target/io-cmd-passthru.c
>>>>> @@ -410,6 +410,9 @@ static struct request *nvmet_passthru_blk_make_request(struct nvmet_req *req,
>>>>> if (unlikely(IS_ERR(rq)))
>>>>> return rq;
>>>>>
>>>>> + if (blk_queue_io_stat(q) && cmd->common.opcode != nvme_cmd_flush)
>>>>> + rq->rq_flags |= RQF_IO_STAT;
>>>
>>> Thanks for the review!
>>>
>>>> Does flush has data bytes in the request? Why the special casing?
>>>
>>> Well it was special cased in the vanilla blk account flow... But I think
>>> it's required to be special cased so the IO and in_flight counts don't
>>> count flushes (as they do not for regular block device traffic).
>>
>> I think that the accounting exclude I/O that is yielded from the flush
>> sequence. Don't think its relevant here...
>
> What? Per blk_account_io_done(), RQF_FLUSH_SEQ will not be set by us for
> passthru commands and I don't think it's appropriate to do so. Thus, if
> we set RQF_IO_STAT for passthru flush commands, they will be counted
> which we do not want.
Have you considered to have nvmet_passthru_blk_make_request set RQF_FUA
for nvme_cmd_flush? this way blk_insert_flush will be called and
RQF_FLUSH_SEQ will be set and you don't need to worry about this
special casing...
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next prev parent reply other threads:[~2019-09-09 23:15 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190828215429.4572-1-logang@deltatee.com>
[not found] ` <20190828215429.4572-2-logang@deltatee.com>
2019-09-06 23:33 ` [PATCH v8 01/13] nvme-core: introduce nvme_ctrl_get_by_path() Sagi Grimberg
[not found] ` <20190828215429.4572-3-logang@deltatee.com>
2019-09-06 23:33 ` [PATCH v8 02/13] nvme-core: export existing ctrl and ns interfaces Sagi Grimberg
[not found] ` <20190828215429.4572-4-logang@deltatee.com>
2019-09-06 23:34 ` [PATCH v8 03/13] nvmet: add return value to nvmet_add_async_event() Sagi Grimberg
[not found] ` <20190828215429.4572-5-logang@deltatee.com>
2019-09-06 23:34 ` [PATCH v8 04/13] nvmet: make nvmet_copy_ns_identifier() non-static Sagi Grimberg
[not found] ` <20190828215429.4572-6-logang@deltatee.com>
2019-09-06 23:35 ` [PATCH v8 05/13] nvmet-passthru: update KConfig with config passthru option Sagi Grimberg
[not found] ` <20190828215429.4572-9-logang@deltatee.com>
2019-09-06 23:38 ` [PATCH v8 08/13] nvmet-core: don't check the data len for pt-ctrl Sagi Grimberg
[not found] ` <20190828215429.4572-10-logang@deltatee.com>
2019-09-06 23:39 ` [PATCH v8 09/13] nvmet-tcp: don't check data_len in nvmet_tcp_map_data() Sagi Grimberg
[not found] ` <20190828215429.4572-11-logang@deltatee.com>
2019-09-06 23:39 ` [PATCH v8 10/13] nvmet-configfs: introduce passthru configfs interface Sagi Grimberg
[not found] ` <20190828215429.4572-12-logang@deltatee.com>
2019-09-06 23:40 ` [PATCH v8 11/13] block: don't check blk_rq_is_passthrough() in blk_do_io_stat() Sagi Grimberg
[not found] ` <20190828215429.4572-13-logang@deltatee.com>
2019-09-06 23:41 ` [PATCH v8 12/13] block: call blk_account_io_start() in blk_execute_rq_nowait() Sagi Grimberg
[not found] ` <20190828215429.4572-14-logang@deltatee.com>
2019-09-07 0:00 ` [PATCH v8 13/13] nvmet-passthru: support block accounting Sagi Grimberg
2019-09-09 16:06 ` Logan Gunthorpe
2019-09-09 19:26 ` Sagi Grimberg
2019-09-09 19:32 ` Logan Gunthorpe
2019-09-09 23:15 ` Sagi Grimberg [this message]
2019-09-11 16:53 ` Logan Gunthorpe
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