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Re: [Qemu-devel] [PATCH v10 05/14] migration: Create ram_multifd_page
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v10 05/14] migration: Create ram_multifd_page |
Date: |
Tue, 23 Jan 2018 20:16:47 +0000 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
* Juan Quintela (address@hidden) wrote:
> The function still don't use multifd, but we have simplified
> ram_save_page, xbzrle and RDMA stuff is gone. We have added a new
> counter and a new flag for this type of pages.
>
> Signed-off-by: Juan Quintela <address@hidden>
>
> --
> Add last_page parameter
> Add commets for done and address
> Remove multifd field, it is the same than normal pages
> Merge next patch, now we send multiple pages at a time
> Remove counter for multifd pages, it is identical to normal pages
> Use iovec's instead of creating the equivalent.
> Clear memory used by pages (dave)
> Use g_new0(danp)
> define MULTIFD_CONTINUE
> now pages member is a pointer
> Fix off-by-one in number of pages in one packet
> ---
> migration/ram.c | 159
> ++++++++++++++++++++++++++++++++++++++++++++++++-
> migration/trace-events | 2 +
> 2 files changed, 160 insertions(+), 1 deletion(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index aef5a323f3..5d6b46ac23 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -52,6 +52,7 @@
> #include "migration/block.h"
> #include "sysemu/sysemu.h"
> #include "qemu/uuid.h"
> +#include "qemu/iov.h"
>
> /***********************************************************/
> /* ram save/restore */
> @@ -71,6 +72,7 @@
> #define RAM_SAVE_FLAG_XBZRLE 0x40
> /* 0x80 is reserved in migration.h start with 0x100 next */
> #define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100
> +#define RAM_SAVE_FLAG_MULTIFD_PAGE 0x200
>
> static inline bool is_zero_range(uint8_t *p, uint64_t size)
> {
> @@ -395,14 +397,36 @@ static void compress_threads_save_setup(void)
>
> /* Multiple fd's */
>
> +/* used to continue on the same multifd group */
> +#define MULTIFD_CONTINUE UINT16_MAX
> +
> +typedef struct {
> + /* number of used pages */
Telling us it's used doesn't help much; if I understand
right, this is for accumulating them into one large block
before actually sending them?
> + uint32_t used;
> + /* number of allocated pages */
> + uint32_t allocated;
> + /* global number of generated multifd packets */
> + uint32_t seq;
> + struct iovec *iov;
> + RAMBlock *block;
> +} multifd_pages_t;
> +
> struct MultiFDSendParams {
> + /* not changed */
???
> uint8_t id;
> char *name;
> QemuThread thread;
> QIOChannel *c;
> QemuSemaphore sem;
> QemuMutex mutex;
> + /* protected by param mutex */
> bool quit;
> + multifd_pages_t *pages;
> + /* how many patches has sent this channel */
s/patches/packets/
> + uint32_t packets_sent;
> + /* protected by multifd mutex */
> + /* has the thread finish the last submitted job */
> + bool done;
> };
> typedef struct MultiFDSendParams MultiFDSendParams;
>
> @@ -410,8 +434,31 @@ struct {
> MultiFDSendParams *params;
> /* number of created threads */
> int count;
> + QemuMutex mutex;
> + QemuSemaphore sem;
> + multifd_pages_t *pages;
> } *multifd_send_state;
>
> +static void multifd_pages_init(multifd_pages_t **ppages, size_t size)
What is the 'size' here - it's allocated pages for something?
> +{
> + multifd_pages_t *pages = g_new0(multifd_pages_t, 1);
> +
> + pages->allocated = size;
> + pages->iov = g_new0(struct iovec, size);
> + *ppages = pages;
> +}
> +
> +static void multifd_pages_clear(multifd_pages_t *pages)
> +{
> + pages->used = 0;
> + pages->allocated = 0;
> + pages->seq = 0;
> + pages->block = NULL;
> + g_free(pages->iov);
> + pages->iov = NULL;
> + g_free(pages);
> +}
> +
> static void terminate_multifd_send_threads(Error *errp)
> {
> int i;
> @@ -453,9 +500,13 @@ int multifd_save_cleanup(Error **errp)
> socket_send_channel_destroy(p->c);
> g_free(p->name);
> p->name = NULL;
> + multifd_pages_clear(p->pages);
> + p->pages = NULL;
> }
> g_free(multifd_send_state->params);
> multifd_send_state->params = NULL;
> + multifd_pages_clear(multifd_send_state->pages);
> + multifd_send_state->pages = NULL;
> g_free(multifd_send_state);
> multifd_send_state = NULL;
> return ret;
> @@ -482,6 +533,7 @@ static void *multifd_send_thread(void *opaque)
> terminate_multifd_send_threads(local_err);
> return NULL;
> }
> + qemu_sem_post(&multifd_send_state->sem);
>
> while (true) {
> qemu_mutex_lock(&p->mutex);
> @@ -489,9 +541,24 @@ static void *multifd_send_thread(void *opaque)
> qemu_mutex_unlock(&p->mutex);
> break;
> }
> + if (p->pages->used) {
> + p->pages->used = 0;
> + qemu_mutex_unlock(&p->mutex);
> +
> + trace_multifd_send(p->id, p->pages->seq, p->pages->used);
but p->pages->used is just been set to 0?
> + /* ToDo: send page here */
> +
> + qemu_mutex_lock(&multifd_send_state->mutex);
> + p->done = true;
> + p->packets_sent++;
> + qemu_mutex_unlock(&multifd_send_state->mutex);
> + qemu_sem_post(&multifd_send_state->sem);
> + continue;
> + }
> qemu_mutex_unlock(&p->mutex);
> qemu_sem_wait(&p->sem);
> }
> + trace_multifd_send_thread(p->id, p->packets_sent);
>
> return NULL;
> }
> @@ -529,6 +596,10 @@ int multifd_save_setup(void)
> multifd_send_state = g_malloc0(sizeof(*multifd_send_state));
> multifd_send_state->params = g_new0(MultiFDSendParams, thread_count);
> multifd_send_state->count = 0;
> + qemu_mutex_init(&multifd_send_state->mutex);
> + qemu_sem_init(&multifd_send_state->sem, 0);
> + multifd_pages_init(&multifd_send_state->pages,
> + migrate_multifd_page_count());
> for (i = 0; i < thread_count; i++) {
> MultiFDSendParams *p = &multifd_send_state->params[i];
>
> @@ -536,12 +607,58 @@ int multifd_save_setup(void)
> qemu_sem_init(&p->sem, 0);
> p->quit = false;
> p->id = i;
> + p->done = true;
> + multifd_pages_init(&p->pages, migrate_multifd_page_count());
> p->name = g_strdup_printf("multifdsend_%d", i);
> socket_send_channel_create(multifd_new_send_channel_async, p);
> }
> return 0;
> }
>
> +static uint16_t multifd_send_page(RAMBlock *block, ram_addr_t offset,
> + bool last_page)
> +{
> + int i;
> + MultiFDSendParams *p = NULL; /* make happy gcc */
(English: Make gcc happy)
> + multifd_pages_t *pages = multifd_send_state->pages;
> +
> + if (!pages->block) {
> + pages->block = block;
> + }
> +
> + pages->iov[pages->used].iov_base = block->host + offset;
> + pages->iov[pages->used].iov_len = TARGET_PAGE_SIZE;
> + pages->used++;
> +
> + if (!last_page) {
> + if (pages->used < pages->allocated) {
> + return MULTIFD_CONTINUE;
> + }
> + }
I'm confused by this a bit.
Isn't the next bit waiting for a free thread?
> + qemu_sem_wait(&multifd_send_state->sem);
> + qemu_mutex_lock(&multifd_send_state->mutex);
> + for (i = 0; i < multifd_send_state->count; i++) {
> + p = &multifd_send_state->params[i];
> +
> + if (p->done) {
> + p->done = false;
> + break;
> + }
> + }
> + qemu_mutex_unlock(&multifd_send_state->mutex);
> + qemu_mutex_lock(&p->mutex);
> + p->pages->used = 0;
If we're handing the block of pages to the thread, I don't understand
why we zero used here.
> + p->pages->seq = pages->seq + 1;
> + p->pages->block = NULL;
> + multifd_send_state->pages = p->pages;
> + p->pages = pages;
> + qemu_mutex_unlock(&p->mutex);
> + qemu_sem_post(&p->sem);
> +
> + return i;
> +}
> +
> struct MultiFDRecvParams {
> uint8_t id;
> char *name;
> @@ -1070,6 +1187,31 @@ static int ram_save_page(RAMState *rs,
> PageSearchStatus *pss, bool last_stage)
> return pages;
> }
>
> +static int ram_multifd_page(RAMState *rs, PageSearchStatus *pss,
> + bool last_stage)
> +{
> + int pages;
> + uint8_t *p;
> + RAMBlock *block = pss->block;
> + ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
> +
> + p = block->host + offset;
> +
> + pages = save_zero_page(rs, block, offset);
> + if (pages == -1) {
> + ram_counters.transferred +=
> + save_page_header(rs, rs->f, block,
> + offset | RAM_SAVE_FLAG_MULTIFD_PAGE);
> + multifd_send_page(block, offset, rs->migration_dirty_pages == 1);
> + qemu_put_buffer(rs->f, p, TARGET_PAGE_SIZE);
So that's temporary - we're hoping multifd_send_page will do that?
> + ram_counters.transferred += TARGET_PAGE_SIZE;
> + pages = 1;
> + ram_counters.normal++;
> + }
> +
> + return pages;
> +}
> +
> static int do_compress_ram_page(QEMUFile *f, RAMBlock *block,
> ram_addr_t offset)
> {
> @@ -1498,6 +1640,8 @@ static int ram_save_target_page(RAMState *rs,
> PageSearchStatus *pss,
> if (migrate_use_compression() &&
> (rs->ram_bulk_stage || !migrate_use_xbzrle())) {
> res = ram_save_compressed_page(rs, pss, last_stage);
> + } else if (migrate_use_multifd()) {
> + res = ram_multifd_page(rs, pss, last_stage);
> } else {
> res = ram_save_page(rs, pss, last_stage);
> }
> @@ -2878,6 +3022,10 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> if (!migrate_use_compression()) {
> invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE;
> }
> +
> + if (!migrate_use_multifd()) {
> + invalid_flags |= RAM_SAVE_FLAG_MULTIFD_PAGE;
> + }
> /* This RCU critical section can be very long running.
> * When RCU reclaims in the code start to become numerous,
> * it will be necessary to reduce the granularity of this
> @@ -2902,13 +3050,17 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> if (flags & invalid_flags & RAM_SAVE_FLAG_COMPRESS_PAGE) {
> error_report("Received an unexpected compressed page");
> }
> + if (flags & invalid_flags & RAM_SAVE_FLAG_MULTIFD_PAGE) {
> + error_report("Received an unexpected multifd page");
> + }
>
> ret = -EINVAL;
> break;
> }
>
> if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
> - RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
> + RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE |
> + RAM_SAVE_FLAG_MULTIFD_PAGE)) {
> RAMBlock *block = ram_block_from_stream(f, flags);
>
> host = host_from_ram_block_offset(block, addr);
> @@ -2997,6 +3149,11 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> break;
> }
> break;
> +
> + case RAM_SAVE_FLAG_MULTIFD_PAGE:
> + qemu_get_buffer(f, host, TARGET_PAGE_SIZE);
> + break;
> +
> case RAM_SAVE_FLAG_EOS:
> /* normal exit */
> break;
> diff --git a/migration/trace-events b/migration/trace-events
> index 141e773305..61ee21a13e 100644
> --- a/migration/trace-events
> +++ b/migration/trace-events
> @@ -77,6 +77,8 @@ ram_load_postcopy_loop(uint64_t addr, int flags) "@%"
> PRIx64 " %x"
> ram_postcopy_send_discard_bitmap(void) ""
> ram_save_page(const char *rbname, uint64_t offset, void *host) "%s: offset:
> 0x%" PRIx64 " host: %p"
> ram_save_queue_pages(const char *rbname, size_t start, size_t len) "%s:
> start: 0x%zx len: 0x%zx"
> +multifd_send(char id, int seq, int num) "channel %d sequence %d num pages %d"
> +multifd_send_thread(char id, uint32_t packets) "channel %d packets %d"
>
> # migration/migration.c
> await_return_path_close_on_source_close(void) ""
> --
> 2.14.3
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- [Qemu-devel] [RFC 00/14] Multifd, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 02/14] migration: Rename initial_bytes, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 01/14] migration: Make migrate_fd_error() the owner of the Error, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 03/14] migration: Drop current address parameter from save_zero_page(), Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 05/14] migration: Create ram_multifd_page, Juan Quintela, 2018/01/10
- Re: [Qemu-devel] [PATCH v10 05/14] migration: Create ram_multifd_page,
Dr. David Alan Gilbert <=
- [Qemu-devel] [PATCH v10 07/14] migration: Create thread infrastructure for multifd recv side, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 04/14] migration: Start of multiple fd work, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 08/14] migration: Transfer pages over new channels, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 06/14] migration: Send the fd number which we are going to use for this page, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 11/14] LOCAL: use trace events for migration-test, Juan Quintela, 2018/01/10
- [Qemu-devel] [PATCH v10 10/14] migration: Add multifd test, Juan Quintela, 2018/01/10