On Thu, Aug 19, 2021 at 12:31 PM Tyler Hicks tyhicks@linux.microsoft.com wrote:
On 2021-08-19 21:33:43, Zhansaya Bagdauletkyzy wrote:
Since merged pages are copied every time they need to be modified, the write access time is different between shared and non-shared pages. Add ksm_cow_time() function which evaluates latency of these COW breaks. First, 4000 pages are allocated and the time, required to modify 1 byte in every other page, is measured. After this, the pages are merged into 2000 pairs and in each pair, 1 page is modified (i.e. they are decoupled) to detect COW breaks. The time needed to break COW of merged pages is then compared with performance of non-shared pages.
The test is run as follows: ./ksm_tests -C The output: Total size: 15 MiB
Not merged pages: Total time: 0.002185489 s Average speed: 3202.945 MiB/s Merged pages: Total time: 0.004386872 s Average speed: 1595.670 MiB/sSigned-off-by: Zhansaya Bagdauletkyzy zhansayabagdaulet@gmail.com
v2 -> v3:
- address Tyler's feedback
Thanks for incorporating my suggestions! I can confirm that my feedback was completely addressed.
Reviewed-by: Tyler Hicks tyhicks@linux.microsoft.com
Tyler
Reviewed-by: Pavel Tatashin pasha.tatashin@soleen.com