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Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver
From: |
Alberto Garcia |
Subject: |
Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver |
Date: |
Tue, 08 Aug 2017 16:53:08 +0200 |
User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Tue 08 Aug 2017 03:45:44 PM CEST, Manos Pitsidianakis wrote:
> On Tue, Aug 08, 2017 at 03:13:36PM +0200, Alberto Garcia wrote:
>>On Mon 31 Jul 2017 11:54:41 AM CEST, Manos Pitsidianakis wrote:
>>> block/throttle.c uses existing I/O throttle infrastructure inside a
>>> block filter driver. I/O operations are intercepted in the filter's
>>> read/write coroutines, and referred to block/throttle-groups.c
>>>
>>> The driver can be used with the syntax
>>> -drive driver=throttle,file.filename=foo.qcow2, \
>>> limits.iops-total=...,throttle-group=bar
>>
>>Sorry for not having noticed this earlier, but can't you define the
>>throttling group (and its limits) using -object throttle-group ... as
>>shown in the previous patch, and simply reference it here? Or would we
>>have two alternative ways of setting the throttling limits?
>>
>>What happens if you have many -drive lines each one with a different set
>>of limits but with the same throttling group?
>
> The limits of the last one to be processed will win.
That's what the current throttling API does, and I tend to agree that
it's not completely straightforward (a few people have asked me the same
question since this feature is available).
If we're going to add a new API we could eliminate this ambiguity. After
all the previous -drive throttling.iops-total=... would still be
available, wouldn't it?
> So basically if we have anonymous groups, we accept limits in the
> driver options but only without a group-name.
In the commit message you do however have limits and a group name, is
that a mistake?
-drive driver=throttle,file.filename=foo.qcow2, \
limits.iops-total=...,throttle-group=bar
Berto
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Stefan Hajnoczi, 2017/08/01
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Kevin Wolf, 2017/08/03
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Alberto Garcia, 2017/08/08
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Manos Pitsidianakis, 2017/08/08
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver,
Alberto Garcia <=
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Manos Pitsidianakis, 2017/08/08
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Alberto Garcia, 2017/08/08
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Manos Pitsidianakis, 2017/08/09
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Alberto Garcia, 2017/08/09
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Manos Pitsidianakis, 2017/08/09
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Alberto Garcia, 2017/08/09
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Kevin Wolf, 2017/08/09
- Re: [Qemu-block] [PATCH v3 5/7] block: add throttle block filter driver, Manos Pitsidianakis, 2017/08/14