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Re: [PATCH v5 06/12] migration/dirtyrate: Record hash results for each s
From: |
Zheng Chuan |
Subject: |
Re: [PATCH v5 06/12] migration/dirtyrate: Record hash results for each sampled page |
Date: |
Thu, 27 Aug 2020 14:41:39 +0800 |
User-agent: |
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 |
On 2020/8/26 20:35, Dr. David Alan Gilbert wrote:
> * 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.
>
Hi, Dave.
Thank you for review.
OK, i will fix that in V6:)
> Also, I've asked before - do you really want 4KB explicitly - or
> should you just use TARGET_PAGE_SIZE and TARGET_PAGE_BITS ?
>
> Dave
>
TARGET_PAGE_SIZE will be 2M or 1G for HugePage.
As you see, what we get is hash result of every 'virtual' 4K-page.
We care about if it is dirty within 4K length in ramblock, which would be more
accurate than TARGET_PAGE_SIZE which could be 2M or 1G.
On the other hand, the hugepage will be broken up into 4K during migration.
I think it is better we do hash at 'virtual' 4K-page granularity.
>> +
>> /* Take 1s as default for calculation duration */
>> #define DEFAULT_FETCH_DIRTYRATE_TIME_SEC 1
>>
>> --
>> 1.8.3.1
>>
- [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
[PATCH v5 05/12] migration/dirtyrate: move RAMBLOCK_FOREACH_MIGRATABLE into ram.h, Chuan Zheng, 2020/08/24