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Re: [Qemu-devel] [PATCH 11/17] migration: Create thread infrastructure f
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 11/17] migration: Create thread infrastructure for multifd send side |
Date: |
Thu, 2 Feb 2017 12:03:20 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
* Juan Quintela (address@hidden) wrote:
> We make the locking and the transfer of information specific, even if we
> are still transmiting things through the main thread.
>
> Signed-off-by: Juan Quintela <address@hidden>
> ---
> migration/ram.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 52 insertions(+), 1 deletion(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index c71929e..9d7bc64 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -392,17 +392,25 @@ void migrate_compress_threads_create(void)
> /* Multiple fd's */
>
> struct MultiFDSendParams {
> + /* not changed */
> QemuThread thread;
> QIOChannel *c;
> QemuCond cond;
> QemuMutex mutex;
> + /* protected by param mutex */
> bool quit;
> bool started;
> + uint8_t *address;
> + /* protected by multifd mutex */
> + bool done;
> };
> typedef struct MultiFDSendParams MultiFDSendParams;
>
> static MultiFDSendParams *multifd_send;
>
> +QemuMutex multifd_send_mutex;
> +QemuCond multifd_send_cond;
> +
> static void *multifd_send_thread(void *opaque)
> {
> MultiFDSendParams *params = opaque;
> @@ -416,7 +424,17 @@ static void *multifd_send_thread(void *opaque)
>
> qemu_mutex_lock(¶ms->mutex);
> while (!params->quit){
> - qemu_cond_wait(¶ms->cond, ¶ms->mutex);
> + if (params->address) {
> + params->address = 0;
This confused me (I wondered what happens to the 1st block) but
I see in the next patch this gets replaced by something more complex;
so I suggest just using params->dummy and commented it's about
to get replaced.
> + qemu_mutex_unlock(¶ms->mutex);
> + qemu_mutex_lock(&multifd_send_mutex);
> + params->done = true;
> + qemu_cond_signal(&multifd_send_cond);
> + qemu_mutex_unlock(&multifd_send_mutex);
> + qemu_mutex_lock(¶ms->mutex);
> + } else {
> + qemu_cond_wait(¶ms->cond, ¶ms->mutex);
> + }
> }
> qemu_mutex_unlock(¶ms->mutex);
>
> @@ -464,12 +482,16 @@ void migrate_multifd_send_threads_create(void)
> }
> thread_count = migrate_multifd_threads();
> multifd_send = g_new0(MultiFDSendParams, thread_count);
> + qemu_mutex_init(&multifd_send_mutex);
> + qemu_cond_init(&multifd_send_cond);
> for (i = 0; i < thread_count; i++) {
> char thread_name[15];
> qemu_mutex_init(&multifd_send[i].mutex);
> qemu_cond_init(&multifd_send[i].cond);
> multifd_send[i].quit = false;
> multifd_send[i].started = false;
> + multifd_send[i].done = true;
> + multifd_send[i].address = 0;
> multifd_send[i].c = socket_send_channel_create();
> if(!multifd_send[i].c) {
> error_report("Error creating a send channel");
> @@ -487,6 +509,34 @@ void migrate_multifd_send_threads_create(void)
> }
> }
>
> +static int multifd_send_page(uint8_t *address)
> +{
> + int i, thread_count;
> + bool found = false;
> +
> + thread_count = migrate_multifd_threads();
> + qemu_mutex_lock(&multifd_send_mutex);
> + while (!found) {
> + for (i = 0; i < thread_count; i++) {
> + if (multifd_send[i].done) {
> + multifd_send[i].done = false;
> + found = true;
> + break;
> + }
> + }
> + if (!found) {
> + qemu_cond_wait(&multifd_send_cond, &multifd_send_mutex);
> + }
> + }
> + qemu_mutex_unlock(&multifd_send_mutex);
> + qemu_mutex_lock(&multifd_send[i].mutex);
Having a 'multifd_send_mutex' and a
'multifd_send[i].mutex'
is pretty confusing!
> + multifd_send[i].address = address;
> + qemu_cond_signal(&multifd_send[i].cond);
> + qemu_mutex_unlock(&multifd_send[i].mutex);
> +
> + return 0;
> +}
> +
> struct MultiFDRecvParams {
> QemuThread thread;
> QIOChannel *c;
> @@ -1015,6 +1065,7 @@ static int ram_multifd_page(QEMUFile *f,
> PageSearchStatus *pss,
> *bytes_transferred +=
> save_page_header(f, block, offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
> qemu_put_buffer(f, p, TARGET_PAGE_SIZE);
> + multifd_send_page(p);
> *bytes_transferred += TARGET_PAGE_SIZE;
> pages = 1;
> acct_info.norm_pages++;
> --
> 2.9.3
I think I'm pretty OK with this; but we'll see what it looks like
after you think about Paolo's suggestion; it does feel like it should
be possible to do the locking etc simpler; I just don't know how.
Dave
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH 11/17] migration: Create thread infrastructure for multifd send side,
Dr. David Alan Gilbert <=