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From: Andrii Anisov <andrii.anisov@gmail.com>
To: Julien Grall <julien.grall@arm.com>,
	Stefano Stabellini <sstabellini@kernel.org>
Cc: Peng Fan <van.freenix@gmail.com>, Peng Fan <peng.fan@nxp.com>,
	wei.liu2@citrix.com, xen-devel@lists.xen.org
Subject: Re: [PATCH V4] xen/arm: domain_build: allocate lowmem for dom0 as much as possible
Date: Mon, 14 Nov 2016 11:43:30 +0200	[thread overview]
Message-ID: <CAC1Wxdh-ZZi+CzO6C=wOMxu2jFFH7dOky47JpoZx7L8z3COTbw@mail.gmail.com> (raw)
In-Reply-To: <1367603b-6391-0535-744c-264a12e3c0d8@arm.com>

> Could you define unacceptable performance drop? Have you tried to measure
> what would be the impact?

> I know it can be bad, depending on the class of protocols. I think that
> if numbers were provided to demonstrate that bounce buffers (the swiotlb
> in Linux) are too slow for a given use case

Unfortunately I could not come up with exact requirements numbers.
Introducing another memcpy (what bouncing buffer approach does) for
block or network IO would not only reduce the operation performance
but also increase the overall system load.
All what we does for any of our PV driver solutions is avoiding data
copying inside FE-BE pair in order to increase performance, reduce
latency and system load.

Sincerely,
Andrii Anisov.

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Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel

  parent reply	other threads:[~2016-11-14  9:43 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-23  2:55 [PATCH V4] xen/arm: domain_build: allocate lowmem for dom0 as much as possible Peng Fan
2016-10-08  2:25 ` Peng Fan
2016-11-01 14:42 ` Julien Grall
2016-11-01 18:12   ` Stefano Stabellini
2016-11-10  8:30   ` Peng Fan
2016-11-10 13:01     ` Julien Grall
2016-11-11  1:10       ` Peng Fan
2016-11-11  1:41       ` Wei Liu
2016-11-11 11:35 ` Andrii Anisov
2016-11-11 11:59   ` Julien Grall
2016-11-11 14:24     ` Andrii Anisov
2016-11-11 14:39       ` Andrii Anisov
2016-11-11 16:02       ` Julien Grall
2016-11-11 19:27         ` Stefano Stabellini
2016-11-14  8:54           ` Andrii Anisov
2016-11-14  9:11           ` Andrii Anisov
2016-11-14 20:30             ` Julien Grall
2016-11-16 14:49               ` Andrii Anisov
2016-11-14  9:25         ` Andrii Anisov
2016-11-14  9:43         ` Andrii Anisov [this message]
2016-11-14 23:28           ` Stefano Stabellini
2016-11-16 15:28             ` Andrii Anisov
2016-11-17 17:21               ` Stefano Stabellini
2016-11-18 18:00                 ` Stefano Stabellini
2016-11-21 11:04                 ` Andrii Anisov
2016-11-21 17:52                   ` Stefano Stabellini
2016-11-11 19:25       ` Stefano Stabellini

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