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From: Paolo Bonzini <pbonzini@redhat.com>
To: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
	Emanuele Giuseppe Esposito <eesposit@redhat.com>,
	qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, John Snow <jsnow@redhat.com>,
	qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>,
	Max Reitz <mreitz@redhat.com>
Subject: Re: [PATCH v2 6/7] block-copy: atomic .cancelled and .finished fields in BlockCopyCallState
Date: Fri, 21 May 2021 17:02:26 +0200	[thread overview]
Message-ID: <05e94bee-8ee8-e23f-19c1-a7fcb540e080@redhat.com> (raw)
In-Reply-To: <068832dd-c577-0234-4a1d-dfdae6a5b4dd@virtuozzo.com>

On 20/05/21 17:34, Vladimir Sementsov-Ogievskiy wrote:
> 
>> By adding acquire/release pairs, we ensure that .ret and .error_is_read
>> fields are written by block_copy_dirty_clusters before .finished is true.
> 
> As I already said, please, can we live with one mutex for now? finished, 
> ret, error_is_read, all these variables are changing rarely. I doubt 
> that performance is improved by these atomic operations. But complexity 
> of the architecture increases exponentially.

The problem is that these are used outside coroutines. 
load-acquire/store-release is the simplest way to handle a "finished" 
flag really.

Paolo



  reply	other threads:[~2021-05-21 15:03 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-18 10:07 [PATCH v2 0/7] block-copy: protect block-copy internal structures Emanuele Giuseppe Esposito
2021-05-18 10:07 ` [PATCH v2 1/7] block-copy: streamline choice of copy_range vs. read/write Emanuele Giuseppe Esposito
2021-05-20 14:42   ` Vladimir Sementsov-Ogievskiy
2021-05-20 15:06     ` Emanuele Giuseppe Esposito
2021-05-20 15:24       ` Vladimir Sementsov-Ogievskiy
2021-05-21 15:10     ` Paolo Bonzini
2021-05-21 15:48       ` Vladimir Sementsov-Ogievskiy
2021-05-21 16:43         ` Paolo Bonzini
2021-05-21 17:51       ` Vladimir Sementsov-Ogievskiy
2021-05-27  8:20   ` Stefan Hajnoczi
2021-05-27 19:04     ` Paolo Bonzini
2021-05-18 10:07 ` [PATCH v2 2/7] block-copy: improve documentation of BlockCopyTask and BlockCopyState types and functions Emanuele Giuseppe Esposito
2021-05-20 15:00   ` Vladimir Sementsov-Ogievskiy
2021-05-20 15:15     ` Emanuele Giuseppe Esposito
2021-05-18 10:07 ` [PATCH v2 3/7] block-copy: move progress_set_remaining in block_copy_task_end Emanuele Giuseppe Esposito
2021-05-20 15:03   ` Vladimir Sementsov-Ogievskiy
2021-05-18 10:07 ` [PATCH v2 4/7] block-copy: add a CoMutex to the BlockCopyTask list Emanuele Giuseppe Esposito
2021-05-20 15:19   ` Vladimir Sementsov-Ogievskiy
2021-05-25 10:07     ` Emanuele Giuseppe Esposito
2021-05-25 10:25       ` Vladimir Sementsov-Ogievskiy
2021-05-26 14:58         ` Paolo Bonzini
2021-05-26 16:13           ` Vladimir Sementsov-Ogievskiy
2021-05-27  9:07   ` Stefan Hajnoczi
2021-05-18 10:07 ` [PATCH v2 5/7] block-copy: add QemuMutex lock for BlockCopyCallState list Emanuele Giuseppe Esposito
2021-05-20 15:30   ` Vladimir Sementsov-Ogievskiy
2021-05-21 15:01     ` Paolo Bonzini
2021-05-25 10:58       ` Emanuele Giuseppe Esposito
2021-05-26 14:49         ` Paolo Bonzini
2021-05-28 10:53   ` Paolo Bonzini
2021-05-18 10:07 ` [PATCH v2 6/7] block-copy: atomic .cancelled and .finished fields in BlockCopyCallState Emanuele Giuseppe Esposito
2021-05-20 15:34   ` Vladimir Sementsov-Ogievskiy
2021-05-21 15:02     ` Paolo Bonzini [this message]
2021-05-21 15:53       ` Vladimir Sementsov-Ogievskiy
2021-05-21 15:56       ` Vladimir Sementsov-Ogievskiy
2021-05-21 16:47         ` Paolo Bonzini
2021-05-18 10:07 ` [PATCH v2 7/7] block-copy: protect BlockCopyState .method fields Emanuele Giuseppe Esposito
2021-05-21 17:10   ` Vladimir Sementsov-Ogievskiy
2021-05-25 10:18     ` Emanuele Giuseppe Esposito
2021-05-25 11:00       ` Vladimir Sementsov-Ogievskiy
2021-05-26 14:48         ` Paolo Bonzini
2021-05-26 17:18           ` Vladimir Sementsov-Ogievskiy
2021-05-28 10:24             ` Paolo Bonzini
2021-05-28 11:01               ` Paolo Bonzini
2021-05-28 11:52                 ` Vladimir Sementsov-Ogievskiy
2021-05-28 12:44                 ` Vladimir Sementsov-Ogievskiy
2021-05-20 13:47 ` [PATCH v2 0/7] block-copy: protect block-copy internal structures Vladimir Sementsov-Ogievskiy
2021-05-20 14:33   ` Emanuele Giuseppe Esposito
2021-05-27 10:31 ` Stefan Hajnoczi

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