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From: Cong Wang <xiyou.wangcong@gmail.com>
To: John Garry <john.garry@huawei.com>
Cc: iommu@lists.linux-foundation.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [Patch v2 3/3] iommu: avoid taking iova_rbtree_lock twice
Date: Fri, 29 Nov 2019 22:03:45 -0800	[thread overview]
Message-ID: <CAM_iQpXznBnh+bVMu4Ad-doPfr7en9CnWiG8C8mEXmYu6yTgxg@mail.gmail.com> (raw)
In-Reply-To: <dea0de02-cedc-7817-5b04-3888e0e86812@huawei.com>

On Fri, Nov 29, 2019 at 5:34 AM John Garry <john.garry@huawei.com> wrote:
>
> On 29/11/2019 00:48, Cong Wang wrote:
> > Both find_iova() and __free_iova() take iova_rbtree_lock,
> > there is no reason to take and release it twice inside
> > free_iova().
> >
> > Fold them into the critical section by calling the unlock
> > versions instead.
>
> Since generally the iova would be non-NULL, this seems a reasonable
> change (which could be mentioned in the commit log)

I think it is too obvious to mention it. There are many things we can
mention but we should only mention what's necessary, right?

Thanks.

WARNING: multiple messages have this Message-ID (diff)
From: Cong Wang <xiyou.wangcong@gmail.com>
To: John Garry <john.garry@huawei.com>
Cc: iommu@lists.linux-foundation.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [Patch v2 3/3] iommu: avoid taking iova_rbtree_lock twice
Date: Fri, 29 Nov 2019 22:03:45 -0800	[thread overview]
Message-ID: <CAM_iQpXznBnh+bVMu4Ad-doPfr7en9CnWiG8C8mEXmYu6yTgxg@mail.gmail.com> (raw)
In-Reply-To: <dea0de02-cedc-7817-5b04-3888e0e86812@huawei.com>

On Fri, Nov 29, 2019 at 5:34 AM John Garry <john.garry@huawei.com> wrote:
>
> On 29/11/2019 00:48, Cong Wang wrote:
> > Both find_iova() and __free_iova() take iova_rbtree_lock,
> > there is no reason to take and release it twice inside
> > free_iova().
> >
> > Fold them into the critical section by calling the unlock
> > versions instead.
>
> Since generally the iova would be non-NULL, this seems a reasonable
> change (which could be mentioned in the commit log)

I think it is too obvious to mention it. There are many things we can
mention but we should only mention what's necessary, right?

Thanks.
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  reply	other threads:[~2019-11-30  6:04 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-29  0:48 [Patch v2 0/3] iommu: reduce spinlock contention on fast path Cong Wang
2019-11-29  0:48 ` Cong Wang
2019-11-29  0:48 ` [Patch v2 1/3] iommu: match the original algorithm Cong Wang
2019-11-29  0:48   ` Cong Wang
2019-11-29 14:43   ` John Garry
2019-11-29 14:43     ` John Garry
2019-11-30  5:58     ` Cong Wang
2019-11-30  5:58       ` Cong Wang
2019-12-02 10:55       ` John Garry
2019-12-02 10:55         ` John Garry
2019-12-03 19:26         ` Cong Wang
2019-12-03 19:26           ` Cong Wang
2019-12-02 16:58   ` Christoph Hellwig
2019-12-02 16:58     ` Christoph Hellwig
2019-12-03 19:24     ` Cong Wang
2019-12-03 19:24       ` Cong Wang
2019-11-29  0:48 ` [Patch v2 2/3] iommu: optimize iova_magazine_free_pfns() Cong Wang
2019-11-29  0:48   ` Cong Wang
2019-11-29 13:24   ` John Garry
2019-11-29 13:24     ` John Garry
2019-11-30  6:02     ` Cong Wang
2019-11-30  6:02       ` Cong Wang
2019-12-02 10:02       ` John Garry
2019-12-02 10:02         ` John Garry
2019-12-03 19:40         ` Cong Wang
2019-12-03 19:40           ` Cong Wang
2019-12-02 16:59   ` Christoph Hellwig
2019-12-02 16:59     ` Christoph Hellwig
2019-12-03 19:28     ` Cong Wang
2019-12-03 19:28       ` Cong Wang
2019-11-29  0:48 ` [Patch v2 3/3] iommu: avoid taking iova_rbtree_lock twice Cong Wang
2019-11-29  0:48   ` Cong Wang
2019-11-29 13:34   ` John Garry
2019-11-29 13:34     ` John Garry
2019-11-30  6:03     ` Cong Wang [this message]
2019-11-30  6:03       ` Cong Wang
2019-12-17  9:43 ` [Patch v2 0/3] iommu: reduce spinlock contention on fast path Joerg Roedel
2019-12-17  9:43   ` Joerg Roedel
2019-12-18  4:32   ` Cong Wang
2019-12-18  4:32     ` Cong Wang

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