On Sat, Sep 18, 2021 at 1:07 PM Barry Song <21cnbao@xxxxxxxxx> wrote: > > On Sat, Sep 18, 2021 at 12:09 AM Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote: > > > > The init_mm.page_table_lock is used to protect kernel page tables, we > > can use it to serialize splitting vmemmap PMD mappings instead of mmap > > write lock, which can increase the concurrency of vmemmap_remap_free(). > > > > Curious what is the actual benefit we get in user scenarios from this patch, > 1. we set bootargs to reserve hugetlb statically > 2. we "echo" some figures to sys or proc. > > In other words, Who is going to care about this concurrency? Actually, It increase the concurrency between allocations of HugeTLB pages. But it is not my first consideration. There are a lot of users of mmap read lock of init_mm. The mmap write lock is holding through vmemmap_remap_free(), I want to make it does not affect other users of mmap read lock. I suppose a lot of developers are trying to avoid using mmap write lock. I am also one of them. > Can we have some details on this to put in the commit log? For sure. Those judgments above should be placed in the commit log. Thanks.
