On Fri, Aug 04, 2023 at 06:03:27PM +0300, Andrei Gudkov wrote: > Introduces alternative argument calc-time-ms, which is the > the same as calc-time but accepts millisecond value. > Millisecond granularity allows to make predictions whether > migration will succeed or not. To do this, calculate dirty > rate with calc-time-ms set to max allowed downtime, 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-ms | dirty rate MiB/s | > | +----------------+---------------+--------------+ > | | 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.and...@huawei.com>
Acked-by: Peter Xu <pet...@redhat.com> -- Peter Xu
