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Re: [PATCH v7 01/13] multifd: Document the locking of MultiFD{Send/Recv}
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH v7 01/13] multifd: Document the locking of MultiFD{Send/Recv}Params |
Date: |
Tue, 19 Jul 2022 15:31:13 +0100 |
User-agent: |
Mutt/2.2.6 (2022-06-05) |
* Zhang, Chen (chen.zhang@intel.com) wrote:
>
>
> > -----Original Message-----
> > From: Qemu-devel <qemu-devel-
> > bounces+chen.zhang=intel.com@nongnu.org> On Behalf Of Juan Quintela
> > Sent: Tuesday, May 31, 2022 6:43 PM
> > To: qemu-devel@nongnu.org
> > Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>; Philippe Mathieu-
> > Daudé <f4bug@amsat.org>; Yanan Wang <wangyanan55@huawei.com>; Dr.
> > David Alan Gilbert <dgilbert@redhat.com>; Juan Quintela
> > <quintela@redhat.com>; Eduardo Habkost <eduardo@habkost.net>; Peter
> > Xu <peterx@redhat.com>; Leonardo Bras <leobras@redhat.com>
> > Subject: [PATCH v7 01/13] multifd: Document the locking of
> > MultiFD{Send/Recv}Params
> >
> > Reorder the structures so we can know if the fields are:
> > - Read only
> > - Their own locking (i.e. sems)
> > - Protected by 'mutex'
> > - Only for the multifd channel
> >
> > Signed-off-by: Juan Quintela <quintela@redhat.com>
> > ---
> > migration/multifd.h | 90 ++++++++++++++++++++++++++-------------------
> > 1 file changed, 53 insertions(+), 37 deletions(-)
> >
> > diff --git a/migration/multifd.h b/migration/multifd.h index
> > 4d8d89e5e5..345cfdb50c 100644
> > --- a/migration/multifd.h
> > +++ b/migration/multifd.h
> > @@ -65,7 +65,9 @@ typedef struct {
> > } MultiFDPages_t;
> >
> > typedef struct {
> > - /* this fields are not changed once the thread is created */
> > + /* Fiields are only written at creating/deletion time */
>
> S/Fiields/Fields
Thanks, I've fixed that up.
> Thanks
> Chen
>
> > + /* No lock required for them, they are read only */
> > +
> > /* channel number */
> > uint8_t id;
> > /* channel thread name */
> > @@ -74,39 +76,47 @@ typedef struct {
> > QemuThread thread;
> > /* communication channel */
> > QIOChannel *c;
> > - /* sem where to wait for more work */
> > - QemuSemaphore sem;
> > - /* this mutex protects the following parameters */
> > - QemuMutex mutex;
> > - /* is this channel thread running */
> > - bool running;
> > - /* should this thread finish */
> > - bool quit;
> > /* is the yank function registered */
> > bool registered_yank;
> > + /* packet allocated len */
> > + uint32_t packet_len;
> > + /* multifd flags for sending ram */
> > + int write_flags;
> > +
> > + /* sem where to wait for more work */
> > + QemuSemaphore sem;
> > + /* syncs main thread and channels */
> > + QemuSemaphore sem_sync;
> > +
> > + /* this mutex protects the following parameters */
> > + QemuMutex mutex;
> > + /* is this channel thread running */
> > + bool running;
> > + /* should this thread finish */
> > + bool quit;
> > + /* multifd flags for each packet */
> > + uint32_t flags;
> > + /* global number of generated multifd packets */
> > + uint64_t packet_num;
> > /* thread has work to do */
> > int pending_job;
> > - /* array of pages to sent */
> > + /* array of pages to sent.
> > + * The owner of 'pages' depends of 'pending_job' value:
> > + * pending_job == 0 -> migration_thread can use it.
> > + * pending_job != 0 -> multifd_channel can use it.
> > + */
> > MultiFDPages_t *pages;
> > - /* packet allocated len */
> > - uint32_t packet_len;
> > +
> > + /* thread local variables. No locking required */
> > +
> > /* pointer to the packet */
> > MultiFDPacket_t *packet;
> > - /* multifd flags for sending ram */
> > - int write_flags;
> > - /* multifd flags for each packet */
> > - uint32_t flags;
> > /* size of the next packet that contains pages */
> > uint32_t next_packet_size;
> > - /* global number of generated multifd packets */
> > - uint64_t packet_num;
> > - /* thread local variables */
> > /* packets sent through this channel */
> > uint64_t num_packets;
> > /* non zero pages sent through this channel */
> > uint64_t total_normal_pages;
> > - /* syncs main thread and channels */
> > - QemuSemaphore sem_sync;
> > /* buffers to send */
> > struct iovec *iov;
> > /* number of iovs used */
> > @@ -120,7 +130,9 @@ typedef struct {
> > } MultiFDSendParams;
> >
> > typedef struct {
> > - /* this fields are not changed once the thread is created */
> > + /* Fiields are only written at creating/deletion time */
> > + /* No lock required for them, they are read only */
> > +
> > /* channel number */
> > uint8_t id;
> > /* channel thread name */
> > @@ -129,31 +141,35 @@ typedef struct {
> > QemuThread thread;
> > /* communication channel */
> > QIOChannel *c;
> > + /* packet allocated len */
> > + uint32_t packet_len;
> > +
> > + /* syncs main thread and channels */
> > + QemuSemaphore sem_sync;
> > +
> > /* this mutex protects the following parameters */
> > QemuMutex mutex;
> > /* is this channel thread running */
> > bool running;
> > /* should this thread finish */
> > bool quit;
> > + /* multifd flags for each packet */
> > + uint32_t flags;
> > + /* global number of generated multifd packets */
> > + uint64_t packet_num;
> > +
> > + /* thread local variables. No locking required */
> > +
> > + /* pointer to the packet */
> > + MultiFDPacket_t *packet;
> > + /* size of the next packet that contains pages */
> > + uint32_t next_packet_size;
> > + /* packets sent through this channel */
> > + uint64_t num_packets;
> > /* ramblock host address */
> > uint8_t *host;
> > - /* packet allocated len */
> > - uint32_t packet_len;
> > - /* pointer to the packet */
> > - MultiFDPacket_t *packet;
> > - /* multifd flags for each packet */
> > - uint32_t flags;
> > - /* global number of generated multifd packets */
> > - uint64_t packet_num;
> > - /* thread local variables */
> > - /* size of the next packet that contains pages */
> > - uint32_t next_packet_size;
> > - /* packets sent through this channel */
> > - uint64_t num_packets;
> > /* non zero pages recv through this channel */
> > uint64_t total_normal_pages;
> > - /* syncs main thread and channels */
> > - QemuSemaphore sem_sync;
> > /* buffers to recv */
> > struct iovec *iov;
> > /* Pages that are not zero */
> > --
> > 2.35.3
> >
>
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK