From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52819) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dkxou-0003NM-UF for qemu-devel@nongnu.org; Thu, 24 Aug 2017 15:29:37 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dkxor-0005TR-Q7 for qemu-devel@nongnu.org; Thu, 24 Aug 2017 15:29:36 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45552) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dkxor-0005T4-K0 for qemu-devel@nongnu.org; Thu, 24 Aug 2017 15:29:33 -0400 From: "Dr. David Alan Gilbert (git)" Date: Thu, 24 Aug 2017 20:27:22 +0100 Message-Id: <20170824192730.8440-25-dgilbert@redhat.com> In-Reply-To: <20170824192730.8440-1-dgilbert@redhat.com> References: <20170824192730.8440-1-dgilbert@redhat.com> Subject: [Qemu-devel] [RFC v2 24/32] vub+postcopy: madvises List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, maxime.coquelin@redhat.com, a.perevalov@samsung.com, mst@redhat.com, marcandre.lureau@redhat.com Cc: quintela@redhat.com, peterx@redhat.com, lvivier@redhat.com, aarcange@redhat.com, felipe@nutanix.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 5ec54f7d60..d816851c6d 100644 --- a/contrib/libvhost-user/libvhost-user.c +++ b/contrib/libvhost-user/libvhost-user.c @@ -450,11 +450,39 @@ 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; reg_struct.range.start = (uintptr_t)dev_region->mmap_addr; reg_struct.range.len = dev_region->size + dev_region->mmap_offset; -- 2.13.5