Hi Dmitry, Thank you for your response. The mystery is that we are not doing mmap anonymous, and ftrace shows high time for clear page.
I suspect, the file is being unlinked before being opened. But we haven't been able to trace it yet. Regards, Brijesh On Mon, Oct 11, 2021 at 12:38 PM Dmitry Kozlyuk <dmitry.kozl...@gmail.com> wrote: > Hi Brijesh, > > 2021-10-11 10:25 (UTC-0700), Brijesh Singh: > > Hi there, > > We are seeing high mmap time for 1G hugepage during eal memalloc init. > Most > > time is spent for clearing page, each 4k size.. > > It's not clear to me why clear huge pages is called? The code mmaps > rte_map > > file with map_populate and map_shared this shouldn't cause page zeroing. > > I am curious to know how zeroing is forced? > > The kernel clears all anonymous memory before handling it to the user > space. > It is done for security: there may be sensitive data left by previous users > of those pages. > > There is a pending patchset that aims to solve your issue: > https://mails.dpdk.org/archives/dev/2021-October/223723.html > Please see commit messages for some more explanations. > > > As an alternative, I would like to memset from userspace. In my > experiment > > we are noticing memset 1G file is faster that clear huge pages. > > Can you share the numbers? From my experiments, mmap() is just a little > longer then memset() of the same amount of memory, apparently because the > kernel has some extra work to set up the mapping. >
