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Re: [Qemu-devel] [PATCH v13 08/12] migration: Create ram_save_multifd_pa
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v13 08/12] migration: Create ram_save_multifd_page |
Date: |
Mon, 11 Jun 2018 18:33:21 +0100 |
User-agent: |
Mutt/1.10.0 (2018-05-17) |
* 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.
>
> 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
> Remove RAM_SAVE_FLAG_MULTIFD_PAGE
> s/multifd_pages_t/MultiFDPages_t/
> ---
> migration/ram.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 85 insertions(+)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 3e99d48123..28f5cea4d8 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -55,6 +55,7 @@
> #include "sysemu/sysemu.h"
> #include "qemu/uuid.h"
> #include "savevm.h"
> +#include "qemu/iov.h"
>
> /***********************************************************/
> /* ram save/restore */
> @@ -804,8 +805,65 @@ struct {
> QemuSemaphore sem_sync;
> /* global number of generated multifd packets */
> uint32_t seq;
> + /* send channels ready */
> + QemuSemaphore channels_ready;
> } *multifd_send_state;
>
> +static void multifd_send_pages(void)
> +{
> + int i;
> + static int next_channel;
> + MultiFDSendParams *p = NULL; /* make happy gcc */
> + MultiFDPages_t *pages = multifd_send_state->pages;
> +
> + qemu_sem_wait(&multifd_send_state->channels_ready);
> + for (i = next_channel;; i = (i + 1) % migrate_multifd_channels()) {
> + p = &multifd_send_state->params[i];
> +
> + qemu_mutex_lock(&p->mutex);
> + if (!p->pending_job) {
> + p->pending_job++;
> + next_channel = (i + 1) % migrate_multifd_channels();
> + break;
> + }
> + qemu_mutex_unlock(&p->mutex);
> + }
> + p->pages->used = 0;
> + multifd_send_state->seq++;
> + p->seq = multifd_send_state->seq;
> + p->pages->block = NULL;
> + multifd_send_state->pages = p->pages;
> + p->pages = pages;
This function *really* needs a fat comment about the flow of ->pages
because it's pretty hard to follow.
Other than that;
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
> + qemu_mutex_unlock(&p->mutex);
> + qemu_sem_post(&p->sem);
> +}
> +
> +static void multifd_queue_page(RAMBlock *block, ram_addr_t offset)
> +{
> + MultiFDPages_t *pages = multifd_send_state->pages;
> +
> + if (!pages->block) {
> + pages->block = block;
> + }
> +
> + if (pages->block == block) {
> + pages->offset[pages->used] = offset;
> + pages->iov[pages->used].iov_base = block->host + offset;
> + pages->iov[pages->used].iov_len = TARGET_PAGE_SIZE;
> + pages->used++;
> +
> + if (pages->used < pages->allocated) {
> + return;
> + }
> + }
> +
> + multifd_send_pages();
> +
> + if (pages->block != block) {
> + multifd_queue_page(block, offset);
> + }
> +}
> +
> static void multifd_send_terminate_threads(Error *err)
> {
> int i;
> @@ -860,6 +918,7 @@ int multifd_save_cleanup(Error **errp)
> g_free(p->packet);
> p->packet = NULL;
> }
> + qemu_sem_destroy(&multifd_send_state->channels_ready);
> qemu_sem_destroy(&multifd_send_state->sem_sync);
> g_free(multifd_send_state->params);
> multifd_send_state->params = NULL;
> @@ -877,12 +936,17 @@ static void multifd_send_sync_main(void)
> if (!migrate_use_multifd()) {
> return;
> }
> + if (multifd_send_state->pages->used) {
> + multifd_send_pages();
> + }
> for (i = 0; i < migrate_multifd_channels(); i++) {
> MultiFDSendParams *p = &multifd_send_state->params[i];
>
> trace_multifd_send_sync_main_signal(p->id);
>
> qemu_mutex_lock(&p->mutex);
> + multifd_send_state->seq++;
> + p->seq = multifd_send_state->seq;
> p->flags |= MULTIFD_FLAG_SYNC;
> p->pending_job++;
> qemu_mutex_unlock(&p->mutex);
> @@ -937,6 +1001,7 @@ static void *multifd_send_thread(void *opaque)
> if (flags & MULTIFD_FLAG_SYNC) {
> qemu_sem_post(&multifd_send_state->sem_sync);
> }
> + qemu_sem_post(&multifd_send_state->channels_ready);
> } else if (p->quit) {
> qemu_mutex_unlock(&p->mutex);
> break;
> @@ -996,6 +1061,7 @@ int multifd_save_setup(void)
> atomic_set(&multifd_send_state->count, 0);
> multifd_send_state->pages = multifd_pages_init(page_count);
> qemu_sem_init(&multifd_send_state->sem_sync, 0);
> + qemu_sem_init(&multifd_send_state->channels_ready, 0);
>
> for (i = 0; i < thread_count; i++) {
> MultiFDSendParams *p = &multifd_send_state->params[i];
> @@ -1713,6 +1779,23 @@ static int ram_save_page(RAMState *rs,
> PageSearchStatus *pss, bool last_stage)
> return pages;
> }
>
> +static int ram_save_multifd_page(RAMState *rs, RAMBlock *block,
> + ram_addr_t offset)
> +{
> + uint8_t *p;
> +
> + p = block->host + offset;
> +
> + ram_counters.transferred += save_page_header(rs, rs->f, block,
> + offset |
> RAM_SAVE_FLAG_PAGE);
> + multifd_queue_page(block, offset);
> + qemu_put_buffer(rs->f, p, TARGET_PAGE_SIZE);
> + ram_counters.transferred += TARGET_PAGE_SIZE;
> + ram_counters.normal++;
> +
> + return 1;
> +}
> +
> static int do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock
> *block,
> ram_addr_t offset, uint8_t *source_buf)
> {
> @@ -2116,6 +2199,8 @@ static int ram_save_target_page(RAMState *rs,
> PageSearchStatus *pss,
> */
> if (block == rs->last_sent_block && save_page_use_compression(rs)) {
> return compress_page_with_multi_thread(rs, block, offset);
> + } else if (migrate_use_multifd()) {
> + return ram_save_multifd_page(rs, block, offset);
> }
>
> return ram_save_page(rs, pss, last_stage);
> --
> 2.17.0
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
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