From: Paolo Bonzini <pbonzini@redhat.com>
To: "Marc-André Lureau" <marcandre.lureau@gmail.com>,
"Eduardo Habkost" <ehabkost@redhat.com>
Cc: QEMU <qemu-devel@nongnu.org>,
Stefan Hajnoczi <stefanha@redhat.com>,
Richard Henderson <rth@twiddle.net>
Subject: Re: [PATCH 0/2] RFC: add -mem-shared option
Date: Sun, 1 Dec 2019 19:03:08 +0100 [thread overview]
Message-ID: <0a63a6e8-6b44-ce5c-b244-edf8022121c6@redhat.com> (raw)
In-Reply-To: <CAJ+F1CL1s450gUmGK9hzSgk4Y3XSNTzdt2OdU6z65y1hKGjxeQ@mail.gmail.com>
On 01/12/19 16:40, Marc-André Lureau wrote:
>>> The original idea was to always support one NUMA node, so that you could
>>> do "-numa node,memdev=..." to specify a memory backend with -object.
>>> However, this is not possible anymore since
>>>
>>> if (!mc->cpu_index_to_instance_props ||
>>> !mc->get_default_cpu_node_id) {
>>> error_setg(errp, "NUMA is not supported by this machine-type");
>>> return;
>>> }
>>>
>>> has been added to hw/core/numa.c.
>>>
>>> Therefore, I think instead of -mem-shared we should add a "-m
>>> memdev=..." option. This option:
>>>
>>> * would be mutually exclusive with both -mem-path
>>>
>>> * would be handled from allocate_system_memory_nonnuma.
>>>
>>> * could be mutually exclusive "-numa node", or could just be mutually
>>> exclusive with "-numa node,memdev=..." (the logical conclusion of that
>>> however would be an undeprecation of "-numa node,mem=...", so that has
>>> to be taken into account as well).
>> I completely agree we could do this. I just think this misses
>> completely the point of this series, because usability of:
>>
>> -object memory-backend-file,...,share=on,id=mem -m ...,memdev=mem
>>
>> is not much better than the usability of:
>>
>> -object memory-backend-file,...,share=on,id=mem -numa node,memdev=mem
>>
> +1
> Perhaps when all RAM allocation will occur through memory-backend,
> "-mem-shared" could be simply an alias to "-global
> memory-backend.shared=on"
Yes, this is the point. There are two parts in this series:
(1) allowing use of vhost-user on non-NUMA machines
(2) providing syntactic sugar for it
I have no problem with -mem-shared for (2), but it should just be
syntactic sugar for (1). It's okay if -mem-shared is a global variable
rather than an alias for -global; the important part is not to add any
feature that is not available from the QOM-style command line options.
Paolo
next prev parent reply other threads:[~2019-12-01 18:04 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-28 14:15 [PATCH 0/2] RFC: add -mem-shared option Marc-André Lureau
2019-11-28 14:15 ` [PATCH 1/2] memfd: add qemu_memfd_open() Marc-André Lureau
2019-11-28 14:15 ` [PATCH 2/2] Add -mem-shared option Marc-André Lureau
2019-11-28 16:14 ` Eduardo Habkost
2019-11-28 16:28 ` Igor Mammedov
2019-11-28 20:31 ` Marc-André Lureau
2019-11-29 10:07 ` Igor Mammedov
2019-11-29 10:11 ` Paolo Bonzini
2019-11-29 12:01 ` Markus Armbruster
2019-11-29 20:31 ` Eduardo Habkost
2019-11-29 12:16 ` Igor Mammedov
2019-11-29 17:46 ` Paolo Bonzini
2019-12-02 7:39 ` Igor Mammedov
2019-12-02 21:00 ` Eduardo Habkost
2019-12-03 8:56 ` Thomas Huth
2019-12-03 14:43 ` Igor Mammedov
2019-12-09 20:58 ` Eduardo Habkost
2019-12-10 10:34 ` Markus Armbruster
2019-12-10 13:09 ` Igor Mammedov
2019-12-03 21:34 ` Eduardo Habkost
2019-11-28 16:10 ` [PATCH 0/2] RFC: add " Eduardo Habkost
2019-11-29 9:18 ` Igor Mammedov
2019-11-29 9:31 ` Paolo Bonzini
2019-11-29 10:23 ` Igor Mammedov
2019-11-29 11:21 ` Paolo Bonzini
2019-11-29 20:21 ` Eduardo Habkost
2019-12-01 15:40 ` Marc-André Lureau
2019-12-01 18:03 ` Paolo Bonzini [this message]
2019-11-28 16:59 ` Dr. David Alan Gilbert
2019-11-29 9:23 ` Igor Mammedov
2019-12-13 11:39 ` Stefan Hajnoczi
2019-12-13 13:12 ` Igor Mammedov
2019-11-29 4:37 ` no-reply
2019-11-29 5:34 ` no-reply
2019-11-29 7:02 ` Gerd Hoffmann
2019-11-29 7:30 ` Marc-André Lureau
2019-11-29 9:27 ` Daniel P. Berrangé
2019-11-29 9:31 ` Marc-André Lureau
2019-11-29 9:42 ` Daniel P. Berrangé
2019-11-29 9:45 ` Marc-André Lureau
2019-11-29 11:44 ` Gerd Hoffmann
2019-11-29 9:33 ` Paolo Bonzini
2019-11-29 9:39 ` Daniel P. Berrangé
2019-11-29 9:52 ` Paolo Bonzini
2019-11-29 10:13 ` Igor Mammedov
2019-11-29 11:20 ` Paolo Bonzini
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