linux-kernel - Re: [Resend RFC PATCH V2 10/12] HV/IOMMU: Add Hyper-V dma ops support

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Date:   Thu, 13 May 2021 11:19:26 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Tianyu Lan <ltykernel@...il.com>, Christoph Hellwig <hch@....de>,
        konrad.wilk@...cle.com
Cc:     baolu.lu@...ux.intel.com, linux-hyperv@...r.kernel.org,
        brijesh.singh@....com, linux-mm@...ck.org, hpa@...or.com,
        kys@...rosoft.com, will@...nel.org, sunilmut@...rosoft.com,
        linux-arch@...r.kernel.org, wei.liu@...nel.org,
        sthemmin@...rosoft.com, linux-scsi@...r.kernel.org, x86@...nel.org,
        mingo@...hat.com, kuba@...nel.org, jejb@...ux.ibm.com,
        thomas.lendacky@....com, Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        arnd@...db.de, haiyangz@...rosoft.com, bp@...en8.de,
        tglx@...utronix.de, vkuznets@...hat.com,
        martin.petersen@...cle.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        netdev@...r.kernel.org, akpm@...ux-foundation.org,
        robin.murphy@....com, davem@...emloft.net
Subject: Re: [Resend RFC PATCH V2 10/12] HV/IOMMU: Add Hyper-V dma ops support

On 5/13/21 12:01 AM, Tianyu Lan wrote:
> Hi Christoph and Konrad:
>       Current Swiotlb bounce buffer uses a pool for all devices. There
> is a high overhead to get or free bounce buffer during performance test.
> Swiotlb code now use a global spin lock to protect bounce buffer data.
> Several device queues try to acquire the spin lock and this introduce
> additional overhead.
> 
> For performance and security perspective, each devices should have a
> separate swiotlb bounce buffer pool and so this part needs to rework.
> I want to check this is right way to resolve performance issues with 
> swiotlb bounce buffer. If you have some other suggestions,welcome.

Is this what you want?

https://lore.kernel.org/linux-iommu/20210510095026.3477496-1-tientzu@chromium.org/

Best regards,
baolu