在 2020/3/3 上午6:11, Andrew Morton 写道:
>> - if (PageLRU(page)) {
>> + if (TestClearPageLRU(page)) {
>> lruvec = mem_cgroup_page_lruvec(page, pgdat);
>> - ClearPageLRU(page);
>> del_page_from_lru_list(page, lruvec, page_lru(page));
>> } else
>
> The code will now get exclusive access of the page->flags cacheline and
> will dirty that cacheline, even for !PageLRU() pages. What is the
> performance impact of this?
>
Hi Andrew,
Thanks a lot for comments!
I was tested the whole patchset with fengguang's case-lru-file-readtwice
https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/
which is most sensitive case on PageLRU I found. There are no clear performance
drop.
On this single patch, I just test the same case again, there is still no perf
drop. some data is here on my 96 threads machine:
no lock_dep w lock_dep and few other debug option
w this patch, 50.96MB/s 32.93MB/s
w/o this patch, 50.50MB/s 33.53MB/s
And also no any warning from Intel 0day yet.
Thanks a lot!
Alex
