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[Qemu-devel] [RFC v2 24/32] vub+postcopy: madvises
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [RFC v2 24/32] vub+postcopy: madvises |
Date: |
Thu, 24 Aug 2017 20:27:22 +0100 |
From: "Dr. David Alan Gilbert" <address@hidden>
Clear the area and turn off THP.
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
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
- [Qemu-devel] [RFC v2 17/32] vhost+postcopy: Stash RAMBlock and offset, (continued)
- [Qemu-devel] [RFC v2 17/32] vhost+postcopy: Stash RAMBlock and offset, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 18/32] vhost+postcopy: Send requests to source for shared pages, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 19/32] vhost+postcopy: Resolve client address, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 20/32] postcopy: wake shared, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 21/32] postcopy: postcopy_notify_shared_wake, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 22/32] vhost+postcopy: Add vhost waker, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 23/32] vhost+postcopy: Call wakeups, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 24/32] vub+postcopy: madvises,
Dr. David Alan Gilbert (git) <=
- [Qemu-devel] [RFC v2 25/32] vhost+postcopy: Lock around set_mem_table, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 26/32] vhost: Add VHOST_USER_POSTCOPY_END message, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 27/32] vhost+postcopy: Wire up POSTCOPY_END notify, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 28/32] postcopy: Allow shared memory, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 29/32] vhost-user: Claim support for postcopy, Dr. David Alan Gilbert (git), 2017/08/24