From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Rapoport Subject: [PATCH man-pages 4/5] userfaultfd.2: add note about asynchronios events delivery Date: Mon, 1 May 2017 08:43:18 +0300 Message-ID: <1493617399-20897-5-git-send-email-rppt@linux.vnet.ibm.com> References: <1493617399-20897-1-git-send-email-rppt@linux.vnet.ibm.com> Return-path: In-Reply-To: <1493617399-20897-1-git-send-email-rppt@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org To: "Michael Kerrisk (man-pages)" Cc: Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-man@vger.kernel.org, Mike Rapoport List-Id: linux-man@vger.kernel.org Signed-off-by: Mike Rapoport --- man2/userfaultfd.2 | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/man2/userfaultfd.2 b/man2/userfaultfd.2 index 8b89162..f177bba 100644 --- a/man2/userfaultfd.2 +++ b/man2/userfaultfd.2 @@ -112,6 +112,18 @@ created for the child process, which allows userfaultfd monitor to perform user-space paging for the child process. +Unlike page faults which have to be synchronous and require +explicit or implicit wakeup, +all other events are delivered asynchronously and +the non-cooperative process resumes execution as +soon as manager executes +.BR read(2). +The userfaultfd manager should carefully synchronize calls +to UFFDIO_COPY with the events processing. + +The current asynchronous model of the event delivery is optimal for +single threaded non-cooperative userfaultfd manager implementations. + .\" FIXME elaborate about non-cooperating mode, describe its limitations .\" for kernels before 4.11, features added in 4.11 .\" and limitations remaining in 4.11 -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org