From: "Asutosh Das (asd)" <asutoshd@codeaurora.org>
To: Bart Van Assche <bvanassche@acm.org>,
Can Guo <cang@codeaurora.org>,
nguyenb@codeaurora.org, hongwus@codeaurora.org,
linux-scsi@vger.kernel.org, kernel-team@android.com
Cc: Stanley Chu <stanley.chu@mediatek.com>,
Alim Akhtar <alim.akhtar@samsung.com>,
Avri Altman <avri.altman@wdc.com>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Matthias Brugger <matthias.bgg@gmail.com>,
Bean Huo <beanhuo@micron.com>, Jaegeuk Kim <jaegeuk@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Kiwoong Kim <kwmad.kim@samsung.com>,
Satya Tangirala <satyat@google.com>,
open list <linux-kernel@vger.kernel.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-arm-kernel@lists.infradead.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>
Subject: Re: [PATCH v1 2/3] scsi: ufs: Optimize host lock on transfer requests send/compl paths
Date: Mon, 24 May 2021 18:34:04 -0700 [thread overview]
Message-ID: <d4ff8e1a-f368-6720-798a-a2a31a4d41fb@codeaurora.org> (raw)
In-Reply-To: <41a08b3e-122d-4f1a-abbd-4b5730f880b2@acm.org>
On 5/24/2021 1:10 PM, Bart Van Assche wrote:
> On 5/24/21 1:36 AM, Can Guo wrote:
>> Current UFS IRQ handler is completely wrapped by host lock, and because
>> ufshcd_send_command() is also protected by host lock, when IRQ handler
>> fires, not only the CPU running the IRQ handler cannot send new requests,
>> the rest CPUs can neither. Move the host lock wrapping the IRQ handler into
>> specific branches, i.e., ufshcd_uic_cmd_compl(), ufshcd_check_errors(),
>> ufshcd_tmc_handler() and ufshcd_transfer_req_compl(). Meanwhile, to further
>> reduce occpuation of host lock in ufshcd_transfer_req_compl(), host lock is
>> no longer required to call __ufshcd_transfer_req_compl(). As per test, the
>> optimization can bring considerable gain to random read/write performance.
>
> An additional question is whether it is necessary for v3.0 UFS devices
> to serialize the submission path against the completion path? Multiple
> high-performance SCSI LLDs support hardware with separate submission and
> completion queues and hence do not need any serialization between the
> submission and the completion path. I'm asking this because it is likely
> that sooner or later multiqueue support will be added in the UFS
> specification. Benefiting from multiqueue support will require to rework
> locking in the UFS driver anyway.
>
Hi Bart,
No it's not necessary to serialize both the paths. I think this series
attempts to remove this serialization to a certain degree, which is
what's giving the performance improvement.
Even if multiqueue support would be available in the future, I think
this change is apt now for the current available specification.
> Thanks,
>
> Bart.
>
Thanks,
-asd
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
Linux Foundation Collaborative Project
next prev parent reply other threads:[~2021-05-25 1:34 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1621845419-14194-1-git-send-email-cang@codeaurora.org>
2021-05-24 8:36 ` [PATCH v1 1/3] scsi: ufs: Remove a redundant command completion logic in error handler Can Guo
2021-05-24 16:43 ` Bart Van Assche
2021-05-25 4:15 ` Stanley Chu
2021-05-31 7:14 ` Bean Huo
2021-05-24 8:36 ` [PATCH v1 2/3] scsi: ufs: Optimize host lock on transfer requests send/compl paths Can Guo
2021-05-24 20:10 ` Bart Van Assche
2021-05-25 1:34 ` Asutosh Das (asd) [this message]
2021-05-25 8:24 ` Avri Altman
2021-05-28 7:30 ` Avri Altman
2021-06-02 21:18 ` Asutosh Das (asd)
2021-05-25 1:40 ` Can Guo
2021-05-25 16:40 ` Bart Van Assche
2021-05-31 16:04 ` Bean Huo
2021-06-02 2:14 ` Can Guo
2021-06-03 0:18 ` Bart Van Assche
2021-06-03 2:54 ` Stanley Chu
2021-06-04 1:49 ` Can Guo
2021-06-17 2:49 ` Bart Van Assche
2021-06-23 2:04 ` Can Guo
2021-06-28 22:58 ` Bart Van Assche
2021-06-29 5:41 ` Can Guo
2021-07-01 15:57 ` Bart Van Assche
2021-05-24 8:36 ` [PATCH v1 3/3] scsi: ufs: Utilize Transfer Request List Completion Notification Register Can Guo
2021-05-31 16:05 ` Bean Huo
2021-06-03 2:54 ` Stanley Chu
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