On Monday, February 24, 2020 11:16:16 AM -03 Murilo Opsfelder Araújo wrote: > On Monday, February 24, 2020 7:57:03 AM -03 David Hildenbrand wrote: > > On 24.02.20 11:50, David Hildenbrand wrote: > > > On 19.02.20 23:46, Peter Xu wrote: > > >> On Wed, Feb 12, 2020 at 02:42:46PM +0100, David Hildenbrand wrote: > > >>> Factor it out and add a comment. > > >>> > > >>> Reviewed-by: Igor Kotrasinski <i.kotrasi...@partner.samsung.com> > > >>> Acked-by: Murilo Opsfelder Araujo <muri...@linux.ibm.com> > > >>> Reviewed-by: Richard Henderson <richard.hender...@linaro.org> > > >>> Cc: "Michael S. Tsirkin" <m...@redhat.com> > > >>> Cc: Murilo Opsfelder Araujo <muri...@linux.ibm.com> > > >>> Cc: Greg Kurz <gr...@kaod.org> > > >>> Cc: Eduardo Habkost <ehabk...@redhat.com> > > >>> Cc: "Dr. David Alan Gilbert" <dgilb...@redhat.com> > > >>> Cc: Igor Mammedov <imamm...@redhat.com> > > >>> Signed-off-by: David Hildenbrand <da...@redhat.com> > > >>> --- > > >>> > > >>> util/mmap-alloc.c | 21 ++++++++++++--------- > > >>> 1 file changed, 12 insertions(+), 9 deletions(-) > > >>> > > >>> diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c > > >>> index 27dcccd8ec..82f02a2cec 100644 > > >>> --- a/util/mmap-alloc.c > > >>> +++ b/util/mmap-alloc.c > > >>> @@ -82,17 +82,27 @@ size_t qemu_mempath_getpagesize(const char > > >>> *mem_path) > > >>> > > >>> return qemu_real_host_page_size; > > >>> > > >>> } > > >>> > > >>> +static inline size_t mmap_pagesize(int fd) > > >>> +{ > > >>> +#if defined(__powerpc64__) && defined(__linux__) > > >>> + /* Mappings in the same segment must share the same page size */ > > >>> + return qemu_fd_getpagesize(fd); > > >>> +#else > > >>> + return qemu_real_host_page_size; > > >>> +#endif > > >>> +} > > >> > > >> Pure question: This will return 4K even for huge pages on x86, is this > > >> what we want? > > > > > > (was asking myself the same question) I *think* it's intended. It's > > > mainly only used to allocate one additional guard page. The callers of > > > qemu_ram_mmap() make sure that the size is properly aligned (e.g., to > > > huge pages). > > > > > > Of course, a 4k guard page is sufficient - unless we can't use that > > > (special case for ppc64 here). > > > > > > Thanks! > > > > We could rename the function to mmap_guard_pagesize(), thoughts? > > The existing qemu_fd_getpagesize() already returns qemu_real_host_page_size > for non-anonymous mappings (when fd == -1). I think this new > mmap_pagesize() could be dropped in favor of qemu_fd_getpagesize().
s/non-// I mean "for anonymous mappings". > > A side effect of this change would be guard page using a bit more memory for > non-anonymous mapping. Could that be a problem? > > What do you think? > > -- > Murilo -- Murilo