| Message ID | 20180216131625.9639-2-dgilbert@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3,01/29] migrate: Update ram_block_discard_range for shared | expand |
On Fri, Feb 16, 2018 at 01:15:57PM +0000, Dr. David Alan Gilbert (git) wrote: > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > The choice of call to discard a block is getting more complicated > for other cases. We use fallocate PUNCH_HOLE in any file cases; > it works for both hugepage and for tmpfs. > We use the DONTNEED for non-hugepage cases either where they're > anonymous or where they're private. > > Care should be taken when trying other backing files. > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > --- > exec.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++-------------- > trace-events | 3 ++- > 2 files changed, 48 insertions(+), 15 deletions(-) > > diff --git a/exec.c b/exec.c > index e8d7b335b6..b1bb477776 100644 > --- a/exec.c > +++ b/exec.c > @@ -3702,6 +3702,7 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) > } > > if ((start + length) <= rb->used_length) { > + bool need_madvise, need_fallocate; > uint8_t *host_endaddr = host_startaddr + length; > if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { > error_report("ram_block_discard_range: Unaligned end address: %p", > @@ -3711,29 +3712,60 @@ 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); > -#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. > + /* The logic here is messy; > + * madvise DONTNEED fails for hugepages > + * fallocate works on hugepages and shmem > + */ > + need_madvise = (rb->page_size == qemu_host_page_size); > + need_fallocate = rb->fd != -1; > + if (need_fallocate) { > + /* For a file, this causes the area of the file to be zero'd > + * if read, and for hugetlbfs also causes it to be unmapped > + * so a userfault will trigger. > */ > #ifdef CONFIG_FALLOCATE_PUNCH_HOLE > ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, > start, length); > + if (ret) { > + ret = -errno; > + error_report("ram_block_discard_range: Failed to fallocate " > + "%s:%" PRIx64 " +%zx (%d)", > + rb->idstr, start, length, ret); > + goto err; > + } > +#else > + ret = -ENOSYS; > + error_report("ram_block_discard_range: fallocate not available/file" > + "%s:%" PRIx64 " +%zx (%d)", > + rb->idstr, start, length, ret); > + goto err; > #endif > } > - if (ret) { > - ret = -errno; > - error_report("ram_block_discard_range: Failed to discard range " > + if (need_madvise) { > + /* For normal RAM this causes it to be unmapped, > + * for shared memory it causes the local mapping to disappear > + * and to fall back on the file contents (which we just > + * fallocate'd away). > + */ > +#if defined(CONFIG_MADVISE) > + ret = madvise(host_startaddr, length, MADV_DONTNEED); > + if (ret) { > + ret = -errno; > + error_report("ram_block_discard_range: Failed to discard range " > + "%s:%" PRIx64 " +%zx (%d)", > + rb->idstr, start, length, ret); > + goto err; > + } > +#else > + ret = -ENOSYS; > + error_report("ram_block_discard_range: MADVISE not available" > "%s:%" PRIx64 " +%zx (%d)", > rb->idstr, start, length, ret); > + goto err; > +#endif > } > + trace_ram_block_discard_range(rb->idstr, host_startaddr, > + need_madvise, need_fallocate, ret); Nit: worth to log the length too if it's named as "range"? Either with/without: Reviewed-by: Peter Xu <peterx@redhat.com>
* Peter Xu (peterx@redhat.com) wrote: > On Fri, Feb 16, 2018 at 01:15:57PM +0000, Dr. David Alan Gilbert (git) wrote: > > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com> > > > > The choice of call to discard a block is getting more complicated > > for other cases. We use fallocate PUNCH_HOLE in any file cases; > > it works for both hugepage and for tmpfs. > > We use the DONTNEED for non-hugepage cases either where they're > > anonymous or where they're private. > > > > Care should be taken when trying other backing files. > > > > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > --- > > exec.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++-------------- > > trace-events | 3 ++- > > 2 files changed, 48 insertions(+), 15 deletions(-) > > > > diff --git a/exec.c b/exec.c > > index e8d7b335b6..b1bb477776 100644 > > --- a/exec.c > > +++ b/exec.c > > @@ -3702,6 +3702,7 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) > > } > > > > if ((start + length) <= rb->used_length) { > > + bool need_madvise, need_fallocate; > > uint8_t *host_endaddr = host_startaddr + length; > > if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { > > error_report("ram_block_discard_range: Unaligned end address: %p", > > @@ -3711,29 +3712,60 @@ 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); > > -#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. > > + /* The logic here is messy; > > + * madvise DONTNEED fails for hugepages > > + * fallocate works on hugepages and shmem > > + */ > > + need_madvise = (rb->page_size == qemu_host_page_size); > > + need_fallocate = rb->fd != -1; > > + if (need_fallocate) { > > + /* For a file, this causes the area of the file to be zero'd > > + * if read, and for hugetlbfs also causes it to be unmapped > > + * so a userfault will trigger. > > */ > > #ifdef CONFIG_FALLOCATE_PUNCH_HOLE > > ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, > > start, length); > > + if (ret) { > > + ret = -errno; > > + error_report("ram_block_discard_range: Failed to fallocate " > > + "%s:%" PRIx64 " +%zx (%d)", > > + rb->idstr, start, length, ret); > > + goto err; > > + } > > +#else > > + ret = -ENOSYS; > > + error_report("ram_block_discard_range: fallocate not available/file" > > + "%s:%" PRIx64 " +%zx (%d)", > > + rb->idstr, start, length, ret); > > + goto err; > > #endif > > } > > - if (ret) { > > - ret = -errno; > > - error_report("ram_block_discard_range: Failed to discard range " > > + if (need_madvise) { > > + /* For normal RAM this causes it to be unmapped, > > + * for shared memory it causes the local mapping to disappear > > + * and to fall back on the file contents (which we just > > + * fallocate'd away). > > + */ > > +#if defined(CONFIG_MADVISE) > > + ret = madvise(host_startaddr, length, MADV_DONTNEED); > > + if (ret) { > > + ret = -errno; > > + error_report("ram_block_discard_range: Failed to discard range " > > + "%s:%" PRIx64 " +%zx (%d)", > > + rb->idstr, start, length, ret); > > + goto err; > > + } > > +#else > > + ret = -ENOSYS; > > + error_report("ram_block_discard_range: MADVISE not available" > > "%s:%" PRIx64 " +%zx (%d)", > > rb->idstr, start, length, ret); > > + goto err; > > +#endif > > } > > + trace_ram_block_discard_range(rb->idstr, host_startaddr, > > + need_madvise, need_fallocate, ret); > > Nit: worth to log the length too if it's named as "range"? Done. > Either with/without: > > Reviewed-by: Peter Xu <peterx@redhat.com> Thanks. Dave > > -- > Peter Xu -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/exec.c b/exec.c index e8d7b335b6..b1bb477776 100644 --- a/exec.c +++ b/exec.c @@ -3702,6 +3702,7 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length) } if ((start + length) <= rb->used_length) { + bool need_madvise, need_fallocate; uint8_t *host_endaddr = host_startaddr + length; if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { error_report("ram_block_discard_range: Unaligned end address: %p", @@ -3711,29 +3712,60 @@ 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); -#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. + /* The logic here is messy; + * madvise DONTNEED fails for hugepages + * fallocate works on hugepages and shmem + */ + need_madvise = (rb->page_size == qemu_host_page_size); + need_fallocate = rb->fd != -1; + if (need_fallocate) { + /* For a file, this causes the area of the file to be zero'd + * if read, and for hugetlbfs also causes it to be unmapped + * so a userfault will trigger. */ #ifdef CONFIG_FALLOCATE_PUNCH_HOLE ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, start, length); + if (ret) { + ret = -errno; + error_report("ram_block_discard_range: Failed to fallocate " + "%s:%" PRIx64 " +%zx (%d)", + rb->idstr, start, length, ret); + goto err; + } +#else + ret = -ENOSYS; + error_report("ram_block_discard_range: fallocate not available/file" + "%s:%" PRIx64 " +%zx (%d)", + rb->idstr, start, length, ret); + goto err; #endif } - if (ret) { - ret = -errno; - error_report("ram_block_discard_range: Failed to discard range " + if (need_madvise) { + /* For normal RAM this causes it to be unmapped, + * for shared memory it causes the local mapping to disappear + * and to fall back on the file contents (which we just + * fallocate'd away). + */ +#if defined(CONFIG_MADVISE) + ret = madvise(host_startaddr, length, MADV_DONTNEED); + if (ret) { + ret = -errno; + error_report("ram_block_discard_range: Failed to discard range " + "%s:%" PRIx64 " +%zx (%d)", + rb->idstr, start, length, ret); + goto err; + } +#else + ret = -ENOSYS; + error_report("ram_block_discard_range: MADVISE not available" "%s:%" PRIx64 " +%zx (%d)", rb->idstr, start, length, ret); + goto err; +#endif } + trace_ram_block_discard_range(rb->idstr, host_startaddr, + need_madvise, need_fallocate, ret); } else { error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64 "/%zx/" RAM_ADDR_FMT")", diff --git a/trace-events b/trace-events index ec95e67089..bf9741d930 100644 --- a/trace-events +++ b/trace-events @@ -55,9 +55,10 @@ dma_complete(void *dbs, int ret, void *cb) "dbs=%p ret=%d cb=%p" dma_blk_cb(void *dbs, int ret) "dbs=%p ret=%d" dma_map_wait(void *dbs) "dbs=%p" -# # exec.c +# exec.c find_ram_offset(uint64_t size, uint64_t offset) "size: 0x%" PRIx64 " @ 0x%" PRIx64 find_ram_offset_loop(uint64_t size, uint64_t candidate, uint64_t offset, uint64_t next, uint64_t mingap) "trying size: 0x%" PRIx64 " @ 0x%" PRIx64 ", offset: 0x%" PRIx64" next: 0x%" PRIx64 " mingap: 0x%" PRIx64 +ram_block_discard_range(const char *rbname, void *hva, bool need_madvise, bool need_fallocate, int ret) "%s@%p: madvise: %d fallocate: %d ret: %d" # memory.c memory_region_ops_read(int cpu_index, void *mr, uint64_t addr, uint64_t value, unsigned size) "cpu %d mr %p addr 0x%"PRIx64" value 0x%"PRIx64" size %u"