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2023-10-10migration/calc-dirty-rate: millisecond-granularity periodAndrei Gudkov
This patch allows to measure dirty page rate for sub-second intervals of time. An optional argument is introduced -- calc-time-unit. For example: {"execute": "calc-dirty-rate", "arguments": {"calc-time": 500, "calc-time-unit": "millisecond"} } Millisecond granularity allows to make predictions whether migration will succeed or not. To do this, calculate dirty rate with calc-time set to max allowed downtime (e.g. 300ms), convert measured rate into volume of dirtied memory, and divide by network throughput. If the value is lower than max allowed downtime, then migration will converge. Measurement results for single thread randomly writing to a 1/4/24GiB memory region: +----------------+-----------------------------------------------+ | calc-time | dirty rate MiB/s | | (milliseconds) +----------------+---------------+--------------+ | | theoretical | page-sampling | dirty-bitmap | | | (at 3M wr/sec) | | | +----------------+----------------+---------------+--------------+ | 1GiB | +----------------+----------------+---------------+--------------+ | 100 | 6996 | 7100 | 3192 | | 200 | 4606 | 4660 | 2655 | | 300 | 3305 | 3280 | 2371 | | 400 | 2534 | 2525 | 2154 | | 500 | 2041 | 2044 | 1871 | | 750 | 1365 | 1341 | 1358 | | 1000 | 1024 | 1052 | 1025 | | 1500 | 683 | 678 | 684 | | 2000 | 512 | 507 | 513 | +----------------+----------------+---------------+--------------+ | 4GiB | +----------------+----------------+---------------+--------------+ | 100 | 10232 | 8880 | 4070 | | 200 | 8954 | 8049 | 3195 | | 300 | 7889 | 7193 | 2881 | | 400 | 6996 | 6530 | 2700 | | 500 | 6245 | 5772 | 2312 | | 750 | 4829 | 4586 | 2465 | | 1000 | 3865 | 3780 | 2178 | | 1500 | 2694 | 2633 | 2004 | | 2000 | 2041 | 2031 | 1789 | +----------------+----------------+---------------+--------------+ | 24GiB | +----------------+----------------+---------------+--------------+ | 100 | 11495 | 8640 | 5597 | | 200 | 11226 | 8616 | 3527 | | 300 | 10965 | 8386 | 2355 | | 400 | 10713 | 8370 | 2179 | | 500 | 10469 | 8196 | 2098 | | 750 | 9890 | 7885 | 2556 | | 1000 | 9354 | 7506 | 2084 | | 1500 | 8397 | 6944 | 2075 | | 2000 | 7574 | 6402 | 2062 | +----------------+----------------+---------------+--------------+ Theoretical values are computed according to the following formula: size * (1 - (1-(4096/size))^(time*wps)) / (time * 2^20), where size is in bytes, time is in seconds, and wps is number of writes per second. Signed-off-by: Andrei Gudkov <gudkov.andrei@huawei.com> Reviewed-by: Hyman Huang <yong.huang@smartx.com> Message-Id: <d802e6b8053eb60fbec1a784cf86f67d9528e0a8.1693895970.git.gudkov.andrei@huawei.com> Signed-off-by: Hyman Huang <yong.huang@smartx.com>
2022-07-20migration/dirtyrate: Refactor dirty page rate calculationHyman Huang(黄勇)
abstract out dirty log change logic into function global_dirty_log_change. abstract out dirty page rate calculation logic via dirty-ring into function vcpu_calculate_dirtyrate. abstract out mathematical dirty page rate calculation into do_calculate_dirtyrate, decouple it from DirtyStat. rename set_sample_page_period to dirty_stat_wait, which is well-understood and will be reused in dirtylimit. handle cpu hotplug/unplug scenario during measurement of dirty page rate. export util functions outside migration. Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn> Reviewed-by: Peter Xu <peterx@redhat.com> Message-Id: <7b6f6f4748d5b3d017b31a0429e630229ae97538.1656177590.git.huangy81@chinatelecom.cn> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2021-11-01migration/dirtyrate: introduce struct and adjust DirtyRateStatHyman Huang(黄勇)
introduce "DirtyRateMeasureMode" to specify what method should be used to calculate dirty rate, introduce "DirtyRateVcpu" to store dirty rate for each vcpu. use union to store stat data of specific mode Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn> Message-Id: <661c98c40f40e163aa58334337af8f3ddf41316a.1624040308.git.huangy81@chinatelecom.cn> Reviewed-by: Peter Xu <peterx@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Signed-off-by: Juan Quintela <quintela@redhat.com>
2021-06-08migration/dirtyrate: make sample page count configurableHyman Huang(黄勇)
introduce optional sample-pages argument in calc-dirty-rate, making sample page count per GB configurable so that more accurate dirtyrate can be calculated. Signed-off-by: Hyman Huang(黄勇) <huangy81@chinatelecom.cn> Message-Id: <3103453a3b2796f929269c99a6ad81a9a7f1f405.1623027729.git.huangy81@chinatelecom.cn> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Wrapped a couple of long lines
2020-09-25migration/dirtyrate: Implement set_sample_page_period() and ↵Chuan Zheng
is_sample_period_valid() Implement is_sample_period_valid() to check if the sample period is vaild and do set_sample_page_period() to sleep specific time between sample actions. Signed-off-by: Chuan Zheng <zhengchuan@huawei.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: David Edmondson <david.edmondson@oracle.com> Reviewed-by: Li Qiang <liq3ea@gmail.com> Message-Id: <1600237327-33618-10-git-send-email-zhengchuan@huawei.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2020-09-25migration/dirtyrate: skip sampling ramblock with size below MIN_RAMBLOCK_SIZEChuan Zheng
In order to sample real RAM, skip ramblock with size below MIN_RAMBLOCK_SIZE which is set as 128M. Signed-off-by: Chuan Zheng <zhengchuan@huawei.com> Reviewed-by: David Edmondson <david.edmondson@oracle.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Li Qiang <liq3ea@gmail.com> Message-Id: <1600237327-33618-9-git-send-email-zhengchuan@huawei.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2020-09-25migration/dirtyrate: Add dirtyrate statistics series functionsChuan Zheng
Add dirtyrate statistics functions to record/update dirtyrate info. Signed-off-by: Chuan Zheng <zhengchuan@huawei.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Li Qiang <liq3ea@gmail.com> Message-Id: <1600237327-33618-5-git-send-email-zhengchuan@huawei.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2020-09-25migration/dirtyrate: Add RamblockDirtyInfo to store sampled page infoChuan Zheng
Add RamblockDirtyInfo to store sampled page info of each ramblock. Signed-off-by: Chuan Zheng <zhengchuan@huawei.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: David Edmondson <david.edmondson@oracle.com> Reviewed-by: Li Qiang <liq3ea@gmail.com> Message-Id: <1600237327-33618-4-git-send-email-zhengchuan@huawei.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
2020-09-25migration/dirtyrate: setup up query-dirtyrate framworkChuan Zheng
Add get_dirtyrate_thread() functions to setup query-dirtyrate framework. Signed-off-by: Chuan Zheng <zhengchuan@huawei.com> Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: David Edmondson <david.edmondson@oracle.com> Reviewed-by: Li Qiang <liq3ea@gmail.com> Message-Id: <1600237327-33618-2-git-send-email-zhengchuan@huawei.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>