Re: [PATCH v6 06/12] migration/dirtyrate: Record hash results for each sampled page

[David Edmondson]

On Saturday, 2020-08-29 at 10:52:51 +08, Chuan Zheng wrote:

> Record hash results for each sampled page, crc32 is taken to calculate
> hash results for each sampled length in TARGET_PAGE_SIZE.
>
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com>

Reviewed-by: David Edmondson <david.edmondson@oracle.com>

> ---
>  migration/dirtyrate.c | 125 
> ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 125 insertions(+)
>
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index 35b5c69..f4967fd 100644
> --- a/migration/dirtyrate.c
> +++ b/migration/dirtyrate.c
> @@ -10,6 +10,7 @@
>   * See the COPYING file in the top-level directory.
>   */
>  
> +#include <zlib.h>
>  #include "qemu/osdep.h"
>  #include "qapi/error.h"
>  #include "cpu.h"
> @@ -68,6 +69,130 @@ static void update_dirtyrate(uint64_t msec)
>      DirtyStat.dirty_rate = dirtyrate;
>  }
>  
> +/*
> + * get hash result for the sampled memory with length of TARGET_PAGE_SIZE
> + * in ramblock, which starts from ramblock base address.
> + */
> +static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info,
> +                                      uint64_t vfn)
> +{
> +    uint32_t crc;
> +
> +    crc = crc32(0, (info->ramblock_addr +
> +                vfn * TARGET_PAGE_SIZE), TARGET_PAGE_SIZE);
> +
> +    return crc;
> +}
> +
> +static int save_ramblock_hash(struct RamblockDirtyInfo *info)
> +{
> +    unsigned int sample_pages_count;
> +    int i;
> +    GRand *rand;
> +
> +    sample_pages_count = info->sample_pages_count;
> +
> +    /* ramblock size less than one page, return success to skip this 
> ramblock */
> +    if (unlikely(info->ramblock_pages == 0 || sample_pages_count == 0)) {
> +        return 0;
> +    }
> +
> +    info->hash_result = g_try_malloc0_n(sample_pages_count,
> +                                        sizeof(uint32_t));
> +    if (!info->hash_result) {
> +        return -1;
> +    }
> +
> +    info->sample_page_vfn = g_try_malloc0_n(sample_pages_count,
> +                                            sizeof(uint64_t));
> +    if (!info->sample_page_vfn) {
> +        g_free(info->hash_result);
> +        return -1;
> +    }
> +
> +    rand  = g_rand_new();
> +    for (i = 0; i < sample_pages_count; i++) {
> +        info->sample_page_vfn[i] = g_rand_int_range(rand, 0,
> +                                                    info->ramblock_pages - 
> 1);
> +        info->hash_result[i] = get_ramblock_vfn_hash(info,
> +                                                     
> info->sample_page_vfn[i]);
> +    }
> +    g_rand_free(rand);
> +
> +    return 0;
> +}
> +
> +static void get_ramblock_dirty_info(RAMBlock *block,
> +                                    struct RamblockDirtyInfo *info,
> +                                    struct DirtyRateConfig *config)
> +{
> +    uint64_t sample_pages_per_gigabytes = config->sample_pages_per_gigabytes;
> +
> +    /* Right shift 30 bits to calc ramblock size in GB */
> +    info->sample_pages_count = (qemu_ram_get_used_length(block) *
> +                                sample_pages_per_gigabytes) >> 30;
> +    /* Right shift TARGET_PAGE_BITS to calc page count */
> +    info->ramblock_pages = qemu_ram_get_used_length(block) >>
> +                           TARGET_PAGE_BITS;
> +    info->ramblock_addr = qemu_ram_get_host_addr(block);
> +    strcpy(info->idstr, qemu_ram_get_idstr(block));
> +}
> +
> +static struct RamblockDirtyInfo *
> +alloc_ramblock_dirty_info(int *block_index,
> +                          struct RamblockDirtyInfo *block_dinfo)
> +{
> +    struct RamblockDirtyInfo *info = NULL;
> +    int index = *block_index;
> +
> +    if (!block_dinfo) {
> +        index = 0;
> +        block_dinfo = g_try_new(struct RamblockDirtyInfo, 1);
> +    } else {
> +        index++;
> +        block_dinfo = g_try_realloc(block_dinfo, (index + 1) *
> +                                    sizeof(struct RamblockDirtyInfo));
> +    }
> +    if (!block_dinfo) {
> +        return NULL;
> +    }
> +
> +    info = &block_dinfo[index];
> +    *block_index = index;
> +    memset(info, 0, sizeof(struct RamblockDirtyInfo));
> +
> +    return block_dinfo;
> +}
> +
> +static int record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo,
> +                                     struct DirtyRateConfig config,
> +                                     int *block_index)
> +{
> +    struct RamblockDirtyInfo *info = NULL;
> +    struct RamblockDirtyInfo *dinfo = NULL;
> +    RAMBlock *block = NULL;
> +    int index = 0;
> +
> +    RAMBLOCK_FOREACH_MIGRATABLE(block) {
> +        dinfo = alloc_ramblock_dirty_info(&index, dinfo);
> +        if (dinfo == NULL) {
> +            return -1;
> +        }
> +        info = &dinfo[index];
> +        get_ramblock_dirty_info(block, info, &config);
> +        if (save_ramblock_hash(info) < 0) {
> +            *block_dinfo = dinfo;
> +            *block_index = index;
> +            return -1;
> +        }
> +    }
> +
> +    *block_dinfo = dinfo;
> +    *block_index = index;
> +
> +    return 0;
> +}
> +
>  static void calculate_dirtyrate(struct DirtyRateConfig config)
>  {
>      /* todo */
> -- 
> 1.8.3.1

dme.
-- 
Please don't stand so close to me.