From: Andrii Anisov <andrii.anisov@gmail.com>
To: Julien Grall <julien.grall@arm.com>,
Julien Grall <julien.grall@gmail.com>
Cc: "andre.przywara@arm.com" <andre.przywara@arm.com>,
Oleksandr Tyshchenko <Oleksandr_Tyshchenko@epam.com>,
"sstabellini@kernel.org" <sstabellini@kernel.org>,
Andrii Anisov <Andrii_Anisov@epam.com>,
"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: [PATCH 1/4] xen/arm: gic: Ensure we have an ISB between ack and do_IRQ()
Date: Fri, 23 Nov 2018 12:09:41 +0200 [thread overview]
Message-ID: <a9f3a72f-37cc-9097-e93e-df7d0d47aa01@gmail.com> (raw)
In-Reply-To: <0c381f5d-59f8-fcee-4a25-8a29af3f2d73@arm.com>
Hello Julien,
On 22.11.18 19:22, Julien Grall wrote:
> My biggest worry is you are doing optimization on a vGIC that is not
> fully compliant with how a GIC should behave (e.g edge vs level) and
> with very fragile locking.
Yep, old VGIC locking looks pretty terrible.
> If you are interested, Andre can provides more details.
Being honest, I'm not fully understand edge vs level problem there. It
would be good to get better view on it.
> I can't comment without any numbers here. Bear in mind that we fixed
> bugs in Xen 4.12 (including spectre/meltdown and missing barriers) that
> wasn't backported to Xen 4.10. It is entirely possible that it
> introduced slowness but it also ensure the code is behaving correctly.
For sure, I know that. It was rather a political decision.
> Anyway, if there are performance regression we should investigate them
> and discuss how we can address/limit them. Similarly for the new vGIC,
> if you think it is too slow, then we need to know why before we get rid
> of the old vGIC.
Yep.
> There are no guest prioritization at the moment. However, we may want to
> introduce it to give priority to one guest over.
But still, processing of IRQs by a hypervisor (e.g. moving them from gic
to vgic for guests IRQs) has a higher priority over any guest execution.
--
Sincerely,
Andrii Anisov.
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next prev parent reply other threads:[~2018-11-23 10:09 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-23 18:17 [PATCH 0/4] xen/arm: GIC fixes and improvement Julien Grall
2018-10-23 18:17 ` [PATCH 1/4] xen/arm: gic: Ensure we have an ISB between ack and do_IRQ() Julien Grall
2018-10-24 9:38 ` Andrii Anisov
2018-10-24 14:41 ` Julien Grall
2018-10-25 14:11 ` Andrii Anisov
2018-10-25 14:22 ` Julien Grall
2018-10-25 17:45 ` Andrii Anisov
2018-10-26 12:49 ` Andrii Anisov
2018-10-26 21:55 ` Julien Grall
2018-10-27 12:14 ` Andrii Anisov
2018-10-28 11:46 ` Julien Grall
2018-10-29 10:06 ` Andrii Anisov
2018-10-29 13:36 ` Julien Grall
2018-10-29 16:16 ` Andrii Anisov
2018-10-29 16:22 ` Julien Grall
2018-10-30 8:07 ` Andrii Anisov
2018-11-09 14:42 ` Andrii Anisov
2018-11-09 17:47 ` Julien Grall
2018-11-19 15:54 ` Andrii Anisov
2018-11-19 16:42 ` Julien Grall
2018-11-20 18:10 ` Andrii Anisov
2018-11-20 18:47 ` Julien Grall
2018-11-22 16:51 ` Andrii Anisov
2018-11-22 17:22 ` Julien Grall
2018-11-23 10:09 ` Andrii Anisov [this message]
2018-11-23 12:18 ` Andre Przywara
2018-11-23 13:04 ` Andrii Anisov
2018-11-30 19:52 ` Andrii Anisov
2018-12-03 13:46 ` Andre Przywara
2018-12-03 13:53 ` Juergen Gross
2018-12-03 14:36 ` Andrii Anisov
2018-12-04 17:16 ` Julien Grall
2018-12-03 15:28 ` Andrii Anisov
2018-11-28 0:30 ` Stefano Stabellini
2018-11-22 18:04 ` Andre Przywara
2018-11-23 12:58 ` Andrii Anisov
2018-11-23 13:27 ` Julien Grall
2018-11-27 13:30 ` Andrii Anisov
2018-11-27 15:13 ` Julien Grall
2018-12-03 12:08 ` Andrii Anisov
2018-12-03 12:17 ` Julien Grall
2018-12-03 12:58 ` Andrii Anisov
2018-12-03 13:10 ` Julien Grall
2018-10-25 17:46 ` Andrii Anisov
2018-11-09 23:02 ` Stefano Stabellini
2018-10-23 18:17 ` [PATCH 2/4] xen/arm: gic: Ensure ordering between read of INTACK and shared data Julien Grall
2018-10-24 15:40 ` Andrii Anisov
2018-11-09 23:02 ` Stefano Stabellini
2018-10-23 18:17 ` [PATCH 3/4] xen/arm: gic: Remove duplicated comment in do_sgi Julien Grall
2018-10-24 10:26 ` Andrii Anisov
2018-11-09 23:03 ` Stefano Stabellini
2018-10-23 18:17 ` [PATCH 4/4] xen/arm: gic: Relax barrier when sending an SGI Julien Grall
2018-10-24 13:32 ` Andrii Anisov
2018-10-24 14:46 ` Julien Grall
2018-10-24 15:40 ` Andrii Anisov
2018-10-24 15:44 ` Julien Grall
2018-11-09 23:14 ` Stefano Stabellini
2018-11-12 12:15 ` Julien Grall
-- strict thread matches above, loose matches on Subject: below --
2018-10-29 16:46 [PATCH 1/4] xen/arm: gic: Ensure we have an ISB between ack and do_IRQ() Andrii Anisov
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