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[PULL 28/29] multifd: Document the locking of MultiFD{Send/Recv}Params
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[PULL 28/29] multifd: Document the locking of MultiFD{Send/Recv}Params |
Date: |
Tue, 19 Jul 2022 18:02:20 +0100 |
From: Juan Quintela <quintela@redhat.com>
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>
Message-Id: <20220531104318.7494-2-quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
dgilbert: Typo fixes from Chen Zhang
---
migration/multifd.h | 66 ++++++++++++++++++++++++++++-----------------
1 file changed, 41 insertions(+), 25 deletions(-)
diff --git a/migration/multifd.h b/migration/multifd.h
index 4d8d89e5e5..519f498643 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 */
+ /* Fields are only written at creating/deletion time */
+ /* 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;
+ /* 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;
- /* is the yank function registered */
- bool registered_yank;
+ /* 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 */
+ /* Fields 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;
- /* 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 */
+
+ /* 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;
/* 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 */
--
2.36.1
- [PULL 07/29] softmmu/dirtylimit: Implement dirty page rate limit, (continued)
- [PULL 07/29] softmmu/dirtylimit: Implement dirty page rate limit, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 11/29] migration: Postcopy preemption preparation on channel creation, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 17/29] migration: Export tls-[creds|hostname|authz] params to cmdline too, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 13/29] migration: Postcopy recover with preempt enabled, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 05/29] accel/kvm/kvm-all: Introduce kvm_dirty_ring_size function, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 16/29] migration: Add helpers to detect TLS capability, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 12/29] migration: Postcopy preemption enablement, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 14/29] migration: Create the postcopy preempt channel asynchronously, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 23/29] tests: Add postcopy preempt tests, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 19/29] migration: Respect postcopy request order in preemption mode, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 28/29] multifd: Document the locking of MultiFD{Send/Recv}Params,
Dr. David Alan Gilbert (git) <=
- [PULL 24/29] migration: remove unreachable code after reading data, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 29/29] migration: Avoid false-positive on non-supported scenarios for zero-copy-send, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 22/29] tests: Add postcopy tls recovery migration test, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 27/29] migration/multifd: Report to user when zerocopy not working, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 18/29] migration: Enable TLS for preempt channel, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 15/29] migration: Add property x-postcopy-preempt-break-huge, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 20/29] tests: Move MigrateCommon upper, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 10/29] migration: Add postcopy-preempt capability, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 26/29] Add dirty-sync-missed-zero-copy migration stat, Dr. David Alan Gilbert (git), 2022/07/19
- [PULL 21/29] tests: Add postcopy tls migration test, Dr. David Alan Gilbert (git), 2022/07/19