From: Paul Durrant <xadimgnik@gmail.com>
To: "'Julien Grall'" <julien@xen.org>,
"'Jan Beulich'" <jbeulich@suse.com>,
"'Oleksandr Tyshchenko'" <olekstysh@gmail.com>
Cc: xen-devel@lists.xenproject.org,
"'Oleksandr Tyshchenko'" <oleksandr_tyshchenko@epam.com>,
"'Stefano Stabellini'" <sstabellini@kernel.org>,
"'Volodymyr Babchuk'" <Volodymyr_Babchuk@epam.com>,
"'Andrew Cooper'" <andrew.cooper3@citrix.com>,
"'Wei Liu'" <wl@xen.org>,
"'Roger Pau Monné'" <roger.pau@citrix.com>,
"'Julien Grall'" <julien.grall@arm.com>
Subject: RE: [PATCH V1 11/16] xen/ioreq: Introduce hvm_domain_has_ioreq_server()
Date: Wed, 16 Sep 2020 09:43:20 +0100 [thread overview]
Message-ID: <002901d68c05$6e7e89c0$4b7b9d40$@xen.org> (raw)
In-Reply-To: <63e51f84-c3ee-a894-5ea2-40cd3b6e26dc@xen.org>
> -----Original Message-----
> From: Julien Grall <julien@xen.org>
> Sent: 16 September 2020 09:39
> To: paul@xen.org; 'Jan Beulich' <jbeulich@suse.com>; 'Oleksandr Tyshchenko' <olekstysh@gmail.com>
> Cc: xen-devel@lists.xenproject.org; 'Oleksandr Tyshchenko' <oleksandr_tyshchenko@epam.com>; 'Stefano
> Stabellini' <sstabellini@kernel.org>; 'Volodymyr Babchuk' <Volodymyr_Babchuk@epam.com>; 'Andrew
> Cooper' <andrew.cooper3@citrix.com>; 'Wei Liu' <wl@xen.org>; 'Roger Pau Monné' <roger.pau@citrix.com>;
> 'Julien Grall' <julien.grall@arm.com>
> Subject: Re: [PATCH V1 11/16] xen/ioreq: Introduce hvm_domain_has_ioreq_server()
>
>
>
> On 16/09/2020 09:13, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Jan Beulich <jbeulich@suse.com>
> >> Sent: 16 September 2020 09:05
> >> To: Oleksandr Tyshchenko <olekstysh@gmail.com>; Paul Durrant <paul@xen.org>
> >> Cc: xen-devel@lists.xenproject.org; Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>; Stefano
> >> Stabellini <sstabellini@kernel.org>; Julien Grall <julien@xen.org>; Volodymyr Babchuk
> >> <Volodymyr_Babchuk@epam.com>; Andrew Cooper <andrew.cooper3@citrix.com>; Wei Liu <wl@xen.org>;
> Roger
> >> Pau Monné <roger.pau@citrix.com>; Julien Grall <julien.grall@arm.com>
> >> Subject: Re: [PATCH V1 11/16] xen/ioreq: Introduce hvm_domain_has_ioreq_server()
> >>
> >> On 10.09.2020 22:22, Oleksandr Tyshchenko wrote:
> >>> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> >>>
> >>> This patch introduces a helper the main purpose of which is to check
> >>> if a domain is using IOREQ server(s).
> >>>
> >>> On Arm the benefit is to avoid calling handle_hvm_io_completion()
> >>> (which implies iterating over all possible IOREQ servers anyway)
> >>> on every return in leave_hypervisor_to_guest() if there is no active
> >>> servers for the particular domain.
> >>>
> >
> > Is this really worth it? The limit on the number of ioreq serves is small... just 8.
>
> When I suggested this, I failed to realize there was only 8 IOREQ
> servers available. However, I would not be surprised if this increase
> long term as we want to use
If that happens then we'll probably want to move (back to) a list rather than an array...
>
> > I doubt you'd be able measure the difference.
> Bear in mind that entry/exit to the hypervisor is pretty "cheap" on Arm
> compare to x86. So we want to avoid doing extra work if it is not necessary.
>
... which will seamlessly deal with this issue.
Paul
> Cheers,
>
> --
> Julien Grall
next prev parent reply other threads:[~2020-09-16 8:43 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-10 20:21 [PATCH V1 00/16] IOREQ feature (+ virtio-mmio) on Arm Oleksandr Tyshchenko
2020-09-10 20:21 ` [PATCH V1 01/16] x86/ioreq: Prepare IOREQ feature for making it common Oleksandr Tyshchenko
2020-09-14 13:52 ` Jan Beulich
2020-09-21 12:22 ` Oleksandr
2020-09-21 12:31 ` Jan Beulich
2020-09-21 12:47 ` Oleksandr
2020-09-21 13:29 ` Jan Beulich
2020-09-21 14:43 ` Oleksandr
2020-09-21 15:28 ` Jan Beulich
2020-09-23 17:22 ` Julien Grall
2020-09-23 18:08 ` Oleksandr
2020-09-10 20:21 ` [PATCH V1 02/16] xen/ioreq: Make x86's IOREQ feature common Oleksandr Tyshchenko
2020-09-14 14:17 ` Jan Beulich
2020-09-21 19:02 ` Oleksandr
2020-09-22 6:33 ` Jan Beulich
2020-09-22 9:58 ` Oleksandr
2020-09-22 10:54 ` Jan Beulich
2020-09-22 15:05 ` Oleksandr
2020-09-22 15:52 ` Jan Beulich
2020-09-23 12:28 ` Oleksandr
2020-09-24 10:58 ` Jan Beulich
2020-09-24 15:38 ` Oleksandr
2020-09-24 15:51 ` Jan Beulich
2020-09-24 18:01 ` Julien Grall
2020-09-25 8:19 ` Paul Durrant
2020-09-30 13:39 ` Oleksandr
2020-09-30 17:47 ` Julien Grall
2020-10-01 6:59 ` Paul Durrant
2020-10-01 8:49 ` Jan Beulich
2020-10-01 8:50 ` Paul Durrant
2020-09-10 20:21 ` [PATCH V1 03/16] xen/ioreq: Make x86's hvm_ioreq_needs_completion() common Oleksandr Tyshchenko
2020-09-14 14:59 ` Jan Beulich
2020-09-22 16:16 ` Oleksandr
2020-09-23 17:27 ` Julien Grall
2020-09-10 20:21 ` [PATCH V1 04/16] xen/ioreq: Provide alias for the handle_mmio() Oleksandr Tyshchenko
2020-09-14 15:10 ` Jan Beulich
2020-09-22 16:20 ` Oleksandr
2020-09-23 17:28 ` Julien Grall
2020-09-23 18:17 ` Oleksandr
2020-09-10 20:21 ` [PATCH V1 05/16] xen/ioreq: Make x86's hvm_mmio_first(last)_byte() common Oleksandr Tyshchenko
2020-09-14 15:13 ` Jan Beulich
2020-09-22 16:24 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 06/16] xen/ioreq: Make x86's hvm_ioreq_(page/vcpu/server) structs common Oleksandr Tyshchenko
2020-09-14 15:16 ` Jan Beulich
2020-09-14 15:59 ` Julien Grall
2020-09-22 16:33 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 07/16] xen/dm: Make x86's DM feature common Oleksandr Tyshchenko
2020-09-14 15:56 ` Jan Beulich
2020-09-22 16:46 ` Oleksandr
2020-09-24 11:03 ` Jan Beulich
2020-09-24 12:47 ` Oleksandr
2020-09-23 17:35 ` Julien Grall
2020-09-23 18:28 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 08/16] xen/mm: Make x86's XENMEM_resource_ioreq_server handling common Oleksandr Tyshchenko
2020-09-10 20:22 ` [PATCH V1 09/16] arm/ioreq: Introduce arch specific bits for IOREQ/DM features Oleksandr Tyshchenko
2020-09-11 10:14 ` Oleksandr
2020-09-16 7:51 ` Jan Beulich
2020-09-22 17:12 ` Oleksandr
2020-09-23 18:03 ` Julien Grall
2020-09-23 20:16 ` Oleksandr
2020-09-24 11:08 ` Jan Beulich
2020-09-24 16:02 ` Oleksandr
2020-09-24 18:02 ` Oleksandr
2020-09-25 6:51 ` Jan Beulich
2020-09-25 9:47 ` Oleksandr
2020-09-26 13:12 ` Julien Grall
2020-09-26 13:18 ` Oleksandr
2020-09-24 16:51 ` Julien Grall
2020-09-24 17:25 ` Julien Grall
2020-09-24 18:22 ` Oleksandr
2020-09-26 13:21 ` Julien Grall
2020-09-26 14:57 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 10/16] xen/mm: Handle properly reference in set_foreign_p2m_entry() on Arm Oleksandr Tyshchenko
2020-09-16 7:17 ` Jan Beulich
2020-09-16 8:50 ` Julien Grall
2020-09-16 8:52 ` Jan Beulich
2020-09-16 8:55 ` Julien Grall
2020-09-22 17:30 ` Oleksandr
2020-09-16 8:08 ` Jan Beulich
2020-09-10 20:22 ` [PATCH V1 11/16] xen/ioreq: Introduce hvm_domain_has_ioreq_server() Oleksandr Tyshchenko
2020-09-16 8:04 ` Jan Beulich
2020-09-16 8:13 ` Paul Durrant
2020-09-16 8:39 ` Julien Grall
2020-09-16 8:43 ` Paul Durrant [this message]
2020-09-22 18:39 ` Oleksandr
2020-09-22 18:23 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 12/16] xen/dm: Introduce xendevicemodel_set_irq_level DM op Oleksandr Tyshchenko
2020-09-26 13:50 ` Julien Grall
2020-09-26 14:21 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 13/16] xen/ioreq: Make x86's invalidate qemu mapcache handling common Oleksandr Tyshchenko
2020-09-16 8:50 ` Jan Beulich
2020-09-22 19:32 ` Oleksandr
2020-09-24 11:16 ` Jan Beulich
2020-09-24 16:45 ` Oleksandr
2020-09-25 7:03 ` Jan Beulich
2020-09-25 13:05 ` Oleksandr
2020-10-02 9:55 ` Oleksandr
2020-10-07 10:38 ` Julien Grall
2020-10-07 12:01 ` Oleksandr
2020-09-10 20:22 ` [PATCH V1 14/16] xen/ioreq: Use guest_cmpxchg64() instead of cmpxchg() Oleksandr Tyshchenko
2020-09-16 9:04 ` Jan Beulich
2020-09-16 9:07 ` Julien Grall
2020-09-16 9:09 ` Paul Durrant
2020-09-16 9:12 ` Julien Grall
2020-09-22 20:05 ` Oleksandr
2020-09-23 18:12 ` Julien Grall
2020-09-23 20:29 ` Oleksandr
2020-09-16 9:07 ` Paul Durrant
2020-09-23 18:05 ` Julien Grall
2020-09-10 20:22 ` [PATCH V1 15/16] libxl: Introduce basic virtio-mmio support on Arm Oleksandr Tyshchenko
2020-09-10 20:22 ` [PATCH V1 16/16] [RFC] libxl: Add support for virtio-disk configuration Oleksandr Tyshchenko
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