From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40896) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dQIEi-0005Rl-K3 for qemu-devel@nongnu.org; Wed, 28 Jun 2017 15:02:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dQIEh-00008W-EN for qemu-devel@nongnu.org; Wed, 28 Jun 2017 15:02:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48090) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dQIEh-00008E-63 for qemu-devel@nongnu.org; Wed, 28 Jun 2017 15:02:47 -0400 From: "Dr. David Alan Gilbert (git)" Date: Wed, 28 Jun 2017 20:00:41 +0100 Message-Id: <20170628190047.26159-24-dgilbert@redhat.com> In-Reply-To: <20170628190047.26159-1-dgilbert@redhat.com> References: <20170628190047.26159-1-dgilbert@redhat.com> Subject: [Qemu-devel] [RFC 23/29] vub+postcopy: madvises List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, a.perevalov@samsung.com, marcandre.lureau@redhat.com, maxime.coquelin@redhat.com, mst@redhat.com, quintela@redhat.com, peterx@redhat.com, lvivier@redhat.com, aarcange@redhat.com From: "Dr. David Alan Gilbert" Clear the area and turn off THP. Signed-off-by: Dr. David Alan Gilbert --- contrib/libvhost-user/libvhost-user.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c index 0658b6e847..ceddeac74f 100644 --- a/contrib/libvhost-user/libvhost-user.c +++ b/contrib/libvhost-user/libvhost-user.c @@ -451,11 +451,39 @@ vu_set_mem_table_exec(VuDev *dev, VhostUserMsg *vmsg) } if (dev->postcopy_listening) { + int ret; /* We should already have an open ufd need to mark each memory * range as ufd. - * Note: Do we need any madvises? Well it's not been accessed - * yet, still probably need no THP to be safe, discard to be safe? */ + + /* Discard any mapping we have here; note I can't use MADV_REMOVE + * or fallocate to make the hole since I don't want to lose + * data that's already arrived in the shared process. + * TODO: How to do hugepage + */ + ret = madvise((void *)dev_region->mmap_addr, + dev_region->size + dev_region->mmap_offset, + MADV_DONTNEED); + if (ret) { + fprintf(stderr, + "%s: Failed to madvise(DONTNEED) region %d: %s\n", + __func__, i, strerror(errno)); + } + /* Turn off transparent hugepages so we dont get lose wakeups + * in neighbouring pages. + * TODO: Turn this backon later. + */ + ret = madvise((void *)dev_region->mmap_addr, + dev_region->size + dev_region->mmap_offset, + MADV_NOHUGEPAGE); + if (ret) { + /* Note: This can happen legally on kernels that are configured + * without madvise'able hugepages + */ + fprintf(stderr, + "%s: Failed to madvise(NOHUGEPAGE) region %d: %s\n", + __func__, i, strerror(errno)); + } struct uffdio_register reg_struct; /* Note: We might need to go back to using mmap_addr and * len + mmap_offset for * huge pages, but then we do hope not to -- 2.13.0