linux-kernel - Re: [PATCH 2/2] ufs: don't use the fair tag sharings

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Message-ID: <31af3339-d90e-f0bd-4c9e-0da9f8728ce4@acm.org>
Date:   Wed, 10 May 2023 08:56:16 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Avri Altman <Avri.Altman@....com>, Ed Tsai <ed.tsai@...iatek.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>
Cc:     "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        "stanley.chu@...iatek.com" <stanley.chu@...iatek.com>,
        "peter.wang@...iatek.com" <peter.wang@...iatek.com>,
        "chun-hung.wu@...iatek.com" <chun-hung.wu@...iatek.com>,
        "alice.chao@...iatek.com" <alice.chao@...iatek.com>,
        "powen.kao@...iatek.com" <powen.kao@...iatek.com>,
        "naomi.chu@...iatek.com" <naomi.chu@...iatek.com>,
        "wsd_upstream@...iatek.com" <wsd_upstream@...iatek.com>
Subject: Re: [PATCH 2/2] ufs: don't use the fair tag sharings

On 5/9/23 22:21, Avri Altman wrote:
> Why it was needed to invent a new flag instead of  just clear 
> BLK_MQ_F_TAG_QUEUE_SHARED?

Hi Avri,

The meaning of BLK_MQ_F_TAG_QUEUE_SHARED is "the tag set is shared
across multiple request queues". Clearing BLK_MQ_F_TAG_QUEUE_SHARED if
the tag set is shared would be wrong: it would break all the code
outside the tag allocation code that tests this flag.

Thanks,

Bart.