From e2fa71f527510387f9d474414eba7f9812c58347 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Fri, 24 Feb 2017 18:28:33 +0000 Subject: postcopy: enhance ram_block_discard_range for hugepages Unfortunately madvise DONTNEED doesn't work on hugepagetlb so use fallocate(FALLOC_FL_PUNCH_HOLE) qemu_fd_getpagesize only sets the page based off a file if the file is from hugetlbfs. Signed-off-by: Dr. David Alan Gilbert Reviewed-by: Juan Quintela Reviewed-by: Laurent Vivier Message-Id: <20170224182844.32452-6-dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert --- exec.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/exec.c b/exec.c index 8ac556a2d4..24cdf64226 100644 --- a/exec.c +++ b/exec.c @@ -46,6 +46,11 @@ #include "sysemu/xen-mapcache.h" #include "trace-root.h" +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE +#include +#include +#endif + #endif #include "exec/cpu-all.h" #include "qemu/rcu_queue.h" @@ -3326,12 +3331,23 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) errno = ENOTSUP; /* If we are missing MADVISE etc */ + if (rb->page_size == qemu_host_page_size) { #if defined(CONFIG_MADVISE) - /* Note: We need the madvise MADV_DONTNEED behaviour of definitely - * freeing the page. - */ - ret = madvise(host_startaddr, length, MADV_DONTNEED); + /* Note: We need the madvise MADV_DONTNEED behaviour of definitely + * freeing the page. + */ + ret = madvise(host_startaddr, length, MADV_DONTNEED); #endif + } else { + /* Huge page case - unfortunately it can't do DONTNEED, but + * it can do the equivalent by FALLOC_FL_PUNCH_HOLE in the + * huge page file. + */ +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE + ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, + start, length); +#endif + } if (ret) { ret = -errno; error_report("ram_block_discard_range: Failed to discard range " -- cgit v1.2.1