From: Tianyu Lan <ltykernel@gmail.com>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-hyperv@vger.kernel.org, brijesh.singh@amd.com,
dave.hansen@linux.intel.com, hpa@zytor.com, kys@microsoft.com,
wei.liu@kernel.org, Andi Kleen <ak@linux.intel.com>,
sthemmin@microsoft.com, x86@kernel.org, decui@microsoft.com,
michael.h.kelley@microsoft.com, mingo@redhat.com,
parri.andrea@gmail.com, thomas.lendacky@amd.com,
Tianyu Lan <Tianyu.Lan@microsoft.com>,
konrad.wilk@oracle.com, haiyangz@microsoft.com, bp@alien8.de,
"krish.sadhukhan@oracle.com" <krish.sadhukhan@oracle.com>,
tglx@linutronix.de, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, vkuznets@redhat.com,
robin.murphy@arm.com,
"kirill.shutemov@linux.intel.com"
<kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH V2 1/2] Swiotlb: Add swiotlb_alloc_from_low_pages switch
Date: Tue, 1 Mar 2022 22:01:27 +0800 [thread overview]
Message-ID: <f76c15c5-9ee4-a825-73c8-223564a26d74@gmail.com> (raw)
In-Reply-To: <20220301115340.GA3077@lst.de>
On 3/1/2022 7:53 PM, Christoph Hellwig wrote:
> On Fri, Feb 25, 2022 at 10:28:54PM +0800, Tianyu Lan wrote:
>> One more perspective is that one device may have multiple queues and
>> each queues should have independent swiotlb bounce buffer to avoid spin
>> lock overhead. The number of queues is only available in the device
>> driver. This means new API needs to be called in the device driver
>> according to queue number.
>
> Well, given how hell bent people are on bounce buffering we might
> need some scalability work there anyway.
According to my test on the local machine with two VMs, Linux guest
without swiotlb bounce buffer or with the fix patch from Andi Kleen can
achieve about 40G/s throughput but it's just 24-25G/s with current
swiotlb code. Otherwise, the spinlock contention also consumes more cpu
usage.
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next prev parent reply other threads:[~2022-03-01 14:01 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 12:23 [PATCH V2 0/2] x86/hyperv/Swiotlb: Add swiotlb_set_alloc_from_low_pages() switch function Tianyu Lan
2022-02-09 12:23 ` [PATCH V2 1/2] Swiotlb: Add swiotlb_alloc_from_low_pages switch Tianyu Lan
2022-02-14 8:19 ` Christoph Hellwig
2022-02-14 11:28 ` Tianyu Lan
2022-02-14 13:58 ` Christoph Hellwig
2022-02-15 15:32 ` Tianyu Lan
2022-02-21 15:14 ` Tianyu Lan
2022-02-22 8:05 ` Christoph Hellwig
2022-02-22 15:07 ` Tianyu Lan
2022-02-22 16:00 ` Christoph Hellwig
2022-02-23 9:46 ` Tianyu Lan
2022-02-25 14:28 ` Tianyu Lan
2022-03-01 11:53 ` Christoph Hellwig
2022-03-01 14:01 ` Tianyu Lan [this message]
2022-02-09 12:23 ` [PATCH V2 2/2] x86/hyperv: Make swiotlb bounce buffer allocation not just from low pages Tianyu Lan
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