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 <dgilbert@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Laurent Vivier <lvivier@redhat.com> Message-Id: <20170224182844.32452-6-dgilbert@redhat.com> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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24
exec.c
24
exec.c
@ -46,6 +46,11 @@
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#include "sysemu/xen-mapcache.h"
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#include "sysemu/xen-mapcache.h"
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#include "trace-root.h"
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#include "trace-root.h"
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#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
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#include <fcntl.h>
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#include <linux/falloc.h>
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#endif
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#endif
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#endif
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#include "exec/cpu-all.h"
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#include "exec/cpu-all.h"
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#include "qemu/rcu_queue.h"
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#include "qemu/rcu_queue.h"
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@ -3326,12 +3331,23 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length)
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errno = ENOTSUP; /* If we are missing MADVISE etc */
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errno = ENOTSUP; /* If we are missing MADVISE etc */
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if (rb->page_size == qemu_host_page_size) {
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#if defined(CONFIG_MADVISE)
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#if defined(CONFIG_MADVISE)
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/* Note: We need the madvise MADV_DONTNEED behaviour of definitely
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/* Note: We need the madvise MADV_DONTNEED behaviour of definitely
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* freeing the page.
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* freeing the page.
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*/
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*/
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ret = madvise(host_startaddr, length, MADV_DONTNEED);
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ret = madvise(host_startaddr, length, MADV_DONTNEED);
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#endif
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#endif
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} else {
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/* Huge page case - unfortunately it can't do DONTNEED, but
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* it can do the equivalent by FALLOC_FL_PUNCH_HOLE in the
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* huge page file.
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*/
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#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
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ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
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start, length);
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#endif
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}
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if (ret) {
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if (ret) {
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ret = -errno;
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ret = -errno;
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error_report("ram_block_discard_range: Failed to discard range "
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error_report("ram_block_discard_range: Failed to discard range "
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