From: Kanchan Joshi <joshi.k@samsung.com>
To: Bart Van Assche <bvanassche@acm.org>
Cc: lsf-pc@lists.linux-foundation.org, linux-block@vger.kernel.org,
linux-nvme@lists.infradead.org, io-uring@vger.kernel.org,
axboe@kernel.dk, hch@lst.de, kbusch@kernel.org,
ming.lei@redhat.com
Subject: Re: [LSF/MM/BPF ATTEND][LSF/MM/BPF Topic] Non-block IO
Date: Sat, 11 Feb 2023 01:04:59 +0530 [thread overview]
Message-ID: <20230210193459.GA9184@green5> (raw)
In-Reply-To: <69443f85-5e16-e3db-23e9-caf915881c92@acm.org>
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On Fri, Feb 10, 2023 at 10:18:08AM -0800, Bart Van Assche wrote:
>On 2/10/23 10:00, Kanchan Joshi wrote:
>>3. DMA cost: is high in presence of IOMMU. Keith posted the work[1],
>>with block IO path, last year. I imagine plumbing to get a bit simpler
>>with passthrough-only support. But what are the other things that must
>>be sorted out to have progress on moving DMA cost out of the fast path?
>
>Are performance numbers available?
Around 55% decline when I checked last (6.1-rcX kernel).
512b randread IOPS with optane, on AMD ryzen 9 box -
when iommu is set to lazy (default config)= 3.1M
when iommmu is disabled or in passthrough mode = 4.9M
>Isn't IOMMU cost something that has already been solved? From https://www.usenix.org/system/files/conference/atc15/atc15-paper-peleg.pdf:
>"Evaluation of our designs under Linux shows that (1)
>they achieve 88.5%–100% of the performance obtained
>without an IOMMU".
Since above numbers are more recent than the paper, this is yet to be
solved.
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next prev parent reply other threads:[~2023-02-10 19:35 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20230210180226epcas5p1bd2e1150de067f8af61de2bbf571594d@epcas5p1.samsung.com>
2023-02-10 18:00 ` [LSF/MM/BPF ATTEND][LSF/MM/BPF Topic] Non-block IO Kanchan Joshi
2023-02-10 18:18 ` Bart Van Assche
2023-02-10 19:34 ` Kanchan Joshi [this message]
2023-02-13 20:24 ` Bart Van Assche
2023-02-10 19:47 ` Jens Axboe
2023-02-14 10:33 ` John Garry
2023-02-10 19:53 ` Jens Axboe
2023-02-13 11:54 ` Sagi Grimberg
2023-04-11 22:48 ` Kanchan Joshi
2023-04-11 22:53 ` Jens Axboe
2023-04-11 23:28 ` Kanchan Joshi
2023-04-12 2:12 ` Jens Axboe
2023-04-12 2:33 ` Ming Lei
2023-04-12 13:26 ` Kanchan Joshi
2023-04-12 13:47 ` Ming Lei
2023-02-10 20:07 ` Clay Mayers
2023-02-11 3:33 ` Ming Lei
2023-02-11 12:06 ` Hannes Reinecke
2023-02-28 16:05 ` John Meneghini
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