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Re: [PATCH v5 06/12] migration/dirtyrate: Record hash results for each s
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [PATCH v5 06/12] migration/dirtyrate: Record hash results for each sampled page |
Date: |
Wed, 26 Aug 2020 13:35:01 +0100 |
User-agent: |
Mutt/1.14.6 (2020-07-11) |
* Chuan Zheng (zhengchuan@huawei.com) wrote:
> Record hash results for each sampled page, crc32 is taken to calculate
> hash results for each sampled 4K-page.
>
> Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
> Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com>
> ---
> migration/dirtyrate.c | 136
> ++++++++++++++++++++++++++++++++++++++++++++++++++
> migration/dirtyrate.h | 15 ++++++
> 2 files changed, 151 insertions(+)
>
> diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
> index f6a94d8..66de426 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 "crypto/hash.h"
> @@ -66,6 +67,141 @@ static void update_dirtyrate(uint64_t msec)
> DirtyStat.dirty_rate = dirtyrate;
> }
>
> +/*
> + * get hash result for the sampled memory with length of 4K byte in ramblock,
> + * which starts from ramblock base address.
> + */
> +static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info,
> + uint64_t vfn)
> +{
> + struct iovec iov_array;
> + uint32_t crc;
> +
> + iov_array.iov_base = info->ramblock_addr +
> + vfn * DIRTYRATE_SAMPLE_PAGE_SIZE;
> + iov_array.iov_len = DIRTYRATE_SAMPLE_PAGE_SIZE;
> +
> + crc = crc32(0, iov_array.iov_base, iov_array.iov_len);
> +
> + return crc;
> +}
> +
> +static int save_ramblock_hash(struct RamblockDirtyInfo *info)
> +{
> + unsigned int sample_pages_count;
> + int i;
> + int ret = -1;
> + GRand *rand = g_rand_new();
> +
> + 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)) {
> + ret = 0;
> + goto out;
> + }
> +
> + info->hash_result = g_try_malloc0_n(sample_pages_count,
> + sizeof(uint32_t));
> + if (!info->hash_result) {
> + ret = -1;
> + goto out;
> + }
> +
> + info->sample_page_vfn = g_try_malloc0_n(sample_pages_count,
> + sizeof(uint64_t));
> + if (!info->sample_page_vfn) {
> + g_free(info->hash_result);
> + ret = -1;
> + goto out;
> + }
> +
> + 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]);
> + }
> + ret = 0;
> +
> +out:
> + g_rand_free(rand);
> + return ret;
> +}
> +
> +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 block size in GB */
> + info->sample_pages_count = (qemu_ram_get_used_length(block) *
> + sample_pages_per_gigabytes) >>
> + DIRTYRATE_PAGE_SHIFT_GB;
> +
> + /* Right shift 12 bits to calc page count in 4KB */
> + info->ramblock_pages = qemu_ram_get_used_length(block) >>
> + DIRTYRATE_PAGE_SHIFT_KB;
> + 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 */
> diff --git a/migration/dirtyrate.h b/migration/dirtyrate.h
> index 8e25d93..e3adead 100644
> --- a/migration/dirtyrate.h
> +++ b/migration/dirtyrate.h
> @@ -24,6 +24,21 @@
> */
> #define RAMBLOCK_INFO_MAX_LEN 256
>
> +/*
> + * Sample page size 4K as default.
> + */
> +#define DIRTYRATE_SAMPLE_PAGE_SIZE 4096
> +
> +/*
> + * Sample page size 4K shift
> + */
> +#define DIRTYRATE_PAGE_SHIFT_KB 12
> +
> +/*
> + * Sample page size 1G shift
> + */
> +#define DIRTYRATE_PAGE_SHIFT_GB 30
Your naming is really odd here; 'PAGE_SHIFT_KB' divides
by 4KB, where as 'PAGE_SHIFT_GB' divices by 1KB.
Simplify this; you can just do >>30 for GB because it's well known;
you don't need a #define constant for simple KB,MB,GB since
we all know them.
Also, I've asked before - do you really want 4KB explicitly - or
should you just use TARGET_PAGE_SIZE and TARGET_PAGE_BITS ?
Dave
> +
> /* Take 1s as default for calculation duration */
> #define DEFAULT_FETCH_DIRTYRATE_TIME_SEC 1
>
> --
> 1.8.3.1
>
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
- Re: [PATCH v5 00/12] *** A Method for evaluating dirty page rate ***, (continued)
[PATCH v5 02/12] migration/dirtyrate: add DirtyRateStatus to denote calculation status, Chuan Zheng, 2020/08/24
[PATCH v5 08/12] migration/dirtyrate: skip sampling ramblock with size below MIN_RAMBLOCK_SIZE, Chuan Zheng, 2020/08/24
[PATCH v5 10/12] migration/dirtyrate: Implement calculate_dirtyrate() function, Chuan Zheng, 2020/08/24
[PATCH v5 09/12] migration/dirtyrate: Implement get_sample_page_period() and block_sample_page_period(), Chuan Zheng, 2020/08/24
[PATCH v5 11/12] migration/dirtyrate: Implement qmp_cal_dirty_rate()/qmp_get_dirty_rate() function, Chuan Zheng, 2020/08/24