Messages in this thread | | | Date | Wed, 27 Mar 2024 14:56:59 -0400 | From | Peter Xu <> | Subject | Re: [PATCH] userfaultfd: early return in dup_userfaultfd() |
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On Wed, Mar 27, 2024 at 05:08:35PM +0800, Peng Zhang wrote: > From: ZhangPeng <zhangpeng362@huawei.com> > > When vma->vm_userfaultfd_ctx.ctx is NULL, vma->vm_flags should have > cleared __VM_UFFD_FLAGS. Therefore, there is no need to down_write or > clear the flag, which will affect fork performance. Fix this by > returning early if octx is NULL in dup_userfaultfd(). > > By applying this patch we can get a 1.3% performance improvement for > lmbench fork_prot. Results are as follows: > base early return > Process fork+exit: 419.1106 413.4804 > > Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
-- Peter Xu
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