Commit 1e7cf8c3 authored by Wei Yang's avatar Wei Yang Committed by Dr. David Alan Gilbert
Browse files

migration/postcopy: unsentmap is not necessary for postcopy 



Commit f3f491fc ('Postcopy: Maintain unsentmap') introduced
unsentmap to track not yet sent pages.

This is not necessary since:

    * unsentmap is a sub-set of bmap before postcopy start
    * unsentmap is the summation of bmap and unsentmap after canonicalizing

This patch just removes it.

Signed-off-by: default avatarWei Yang <richardw.yang@linux.intel.com>
Message-Id: <20190819061843.28642-3-richardw.yang@linux.intel.com>
Reviewed-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
parent 8324ef86

include/exec/ram_addr.h

+0 −6
Original line number Diff line number Diff line
@@ -44,12 +44,6 @@ struct RAMBlock { 
    size_t page_size;

    /* dirty bitmap used during migration */

    unsigned long *bmap;

    /* bitmap of pages that haven't been sent even once

     * only maintained and used in postcopy at the moment

     * where it's used to send the dirtymap at the start

     * of the postcopy phase

     */

    unsigned long *unsentmap;

    /* bitmap of already received pages in postcopy */

    unsigned long *receivedmap;

migration/ram.c

+14 −66
Original line number Diff line number Diff line
@@ -2348,7 +2348,7 @@ static bool get_queued_page(RAMState *rs, PageSearchStatus *pss) 
            dirty = test_bit(page, block->bmap);

            if (!dirty) {

                trace_get_queued_page_not_dirty(block->idstr, (uint64_t)offset,

                       page, test_bit(page, block->unsentmap));

                       page, test_bit(page, block->bmap));

            } else {

                trace_get_queued_page(block->idstr, (uint64_t)offset, page);

            }
@@ -2619,10 +2619,6 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss, 
        }



        pages += tmppages;

        if (pss->block->unsentmap) {

            clear_bit(pss->page, pss->block->unsentmap);

        }



        pss->page++;

    } while ((pss->page & (pagesize_bits - 1)) &&

             offset_in_ramblock(pss->block, pss->page << TARGET_PAGE_BITS));
@@ -2776,8 +2772,6 @@ static void ram_save_cleanup(void *opaque) 
        block->clear_bmap = NULL;

        g_free(block->bmap);

        block->bmap = NULL;

        g_free(block->unsentmap);

        block->unsentmap = NULL;

    }



    xbzrle_cleanup();
@@ -2857,8 +2851,6 @@ void ram_postcopy_migrated_memory_release(MigrationState *ms) 
 * Returns zero on success

 *

 * Callback from postcopy_each_ram_send_discard for each RAMBlock

 * Note: At this point the 'unsentmap' is the processed bitmap combined

 *       with the dirtymap; so a '1' means it's either dirty or unsent.

 *

 * @ms: current migration state

 * @block: RAMBlock to discard
@@ -2867,17 +2859,17 @@ static int postcopy_send_discard_bm_ram(MigrationState *ms, RAMBlock *block) 
{

    unsigned long end = block->used_length >> TARGET_PAGE_BITS;

    unsigned long current;

    unsigned long *unsentmap = block->unsentmap;

    unsigned long *bitmap = block->bmap;



    for (current = 0; current < end; ) {

        unsigned long one = find_next_bit(unsentmap, end, current);

        unsigned long one = find_next_bit(bitmap, end, current);

        unsigned long zero, discard_length;



        if (one >= end) {

            break;

        }



        zero = find_next_zero_bit(unsentmap, end, one + 1);

        zero = find_next_zero_bit(bitmap, end, one + 1);



        if (zero >= end) {

            discard_length = end - one;
@@ -2938,16 +2930,12 @@ static int postcopy_each_ram_send_discard(MigrationState *ms) 
 * clean, not a mix.  This function canonicalizes the bitmaps.

 *

 * @ms: current migration state

 * @unsent_pass: if true we need to canonicalize partially unsent host pages

 *               otherwise we need to canonicalize partially dirty host pages

 * @block: block that contains the page we want to canonicalize

 */

static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass,

                                          RAMBlock *block)

static void postcopy_chunk_hostpages_pass(MigrationState *ms, RAMBlock *block)

{

    RAMState *rs = ram_state;

    unsigned long *bitmap = block->bmap;

    unsigned long *unsentmap = block->unsentmap;

    unsigned int host_ratio = block->page_size / TARGET_PAGE_SIZE;

    unsigned long pages = block->used_length >> TARGET_PAGE_BITS;

    unsigned long run_start;
@@ -2957,13 +2945,8 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, 
        return;

    }



    if (unsent_pass) {

        /* Find a sent page */

        run_start = find_next_zero_bit(unsentmap, pages, 0);

    } else {

    /* Find a dirty page */

    run_start = find_next_bit(bitmap, pages, 0);

    }



    while (run_start < pages) {
@@ -2973,11 +2956,7 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, 
         */

        if (QEMU_IS_ALIGNED(run_start, host_ratio)) {

            /* Find the end of this run */

            if (unsent_pass) {

                run_start = find_next_bit(unsentmap, pages, run_start + 1);

            } else {

            run_start = find_next_zero_bit(bitmap, pages, run_start + 1);

            }

            /*

             * If the end isn't at the start of a host page, then the

             * run doesn't finish at the end of a host page
@@ -2994,9 +2973,6 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, 
            /* Clean up the bitmap */

            for (page = fixup_start_addr;

                 page < fixup_start_addr + host_ratio; page++) {

                /* All pages in this host page are now not sent */

                set_bit(page, unsentmap);



                /*

                 * Remark them as dirty, updating the count for any pages

                 * that weren't previously dirty.
@@ -3005,15 +2981,10 @@ static void postcopy_chunk_hostpages_pass(MigrationState *ms, bool unsent_pass, 
            }

        }



        if (unsent_pass) {

            /* Find the next sent page for the next iteration */

            run_start = find_next_zero_bit(unsentmap, pages, run_start);

        } else {

        /* Find the next dirty page for the next iteration */

        run_start = find_next_bit(bitmap, pages, run_start);

    }

}

}



/**

 * postcopy_chunk_hostpages: discard any partially sent host page
@@ -3033,13 +3004,10 @@ static int postcopy_chunk_hostpages(MigrationState *ms, RAMBlock *block) 
{

    postcopy_discard_send_init(ms, block->idstr);



    /* First pass: Discard all partially sent host pages */

    postcopy_chunk_hostpages_pass(ms, true, block);

    /*

     * Second pass: Ensure that all partially dirty host pages are made

     * fully dirty.

     * Ensure that all partially dirty host pages are made fully dirty.

     */

    postcopy_chunk_hostpages_pass(ms, false, block);

    postcopy_chunk_hostpages_pass(ms, block);



    postcopy_discard_send_finish(ms);

    return 0;
@@ -3077,19 +3045,6 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms) 
    rs->last_page = 0;



    RAMBLOCK_FOREACH_NOT_IGNORED(block) {

        unsigned long pages = block->used_length >> TARGET_PAGE_BITS;

        unsigned long *bitmap = block->bmap;

        unsigned long *unsentmap = block->unsentmap;



        if (!unsentmap) {

            /* We don't have a safe way to resize the sentmap, so

             * if the bitmap was resized it will be NULL at this

             * point.

             */

            error_report("migration ram resized during precopy phase");

            rcu_read_unlock();

            return -EINVAL;

        }

        /* Deal with TPS != HPS and huge pages */

        ret = postcopy_chunk_hostpages(ms, block);

        if (ret) {
@@ -3097,12 +3052,9 @@ int ram_postcopy_send_discard_bitmap(MigrationState *ms) 
            return ret;

        }



        /*

         * Update the unsentmap to be unsentmap = unsentmap | dirty

         */

        bitmap_or(unsentmap, unsentmap, bitmap, pages);

#ifdef DEBUG_POSTCOPY

        ram_debug_dump_bitmap(unsentmap, true, pages);

        ram_debug_dump_bitmap(block->bmap, true,

                              block->used_length >> TARGET_PAGE_BITS);

#endif

    }

    trace_ram_postcopy_send_discard_bitmap();
@@ -3270,10 +3222,6 @@ static void ram_list_init_bitmaps(void) 
            bitmap_set(block->bmap, 0, pages);

            block->clear_bmap_shift = shift;

            block->clear_bmap = bitmap_new(clear_bmap_size(pages, shift));

            if (migrate_postcopy_ram()) {

                block->unsentmap = bitmap_new(pages);

                bitmap_set(block->unsentmap, 0, pages);

            }

        }

    }

}