linux-kernel - Re: [PATCH] iommu/iova: Separate atomic variables to improve performance

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Message-ID: <20190411134312.GC4518@8bytes.org>
Date:   Thu, 11 Apr 2019 15:43:12 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Shaokun Zhang <zhangshaokun@...ilicon.com>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Jinyu Qi <jinyuqi@...wei.com>
Subject: Re: [PATCH] iommu/iova: Separate atomic variables to improve
 performance

On Wed, Apr 03, 2019 at 04:35:21PM +0800, Shaokun Zhang wrote:
> From: Jinyu Qi <jinyuqi@...wei.com> 
> 
> In struct iova_domain, there are three atomic variables, the former two
> are about TLB flush counters which use atomic_add operation, anoter is
> used to flush timer that use cmpxhg operation.
> These variables are in the same cache line, so it will cause some
> performance loss under the condition that many cores call queue_iova
> function, Let's isolate the two type atomic variables to different
> cache line to reduce cache line conflict.
> 
> Cc: Joerg Roedel <joro@...tes.org>
> Signed-off-by: Jinyu Qi <jinyuqi@...wei.com>
> ---
>  include/linux/iova.h | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)

Applied, thanks.