"Dr. David Alan Gilbert" <dgilb...@redhat.com> wrote: > * Juan Quintela (quint...@redhat.com) wrote: >> "Dr. David Alan Gilbert (git)" <dgilb...@redhat.com> wrote: >> > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> >> > >> > 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 <dgilb...@redhat.com>
>> > +#if defined(CONFIG_FALLOCATE_PUNCH_HOLE) >> > +#include <linux/falloc.h> >> > +#endif I hate this in generic code :-() I think that the function will have to be called: qemu_ram_punch_hole(RAMBblock *, length); Put it all together at the beggining of the file? What I don't want is that if someone arrives with a way to do this in other OS, we need to put yet more ifdefs. I preffer very much that it just have to define a function with that semantics. Agreed that this is a mess, but I can't think of an easier way of doing it either :-() >> > @@ -1874,15 +1878,27 @@ int ram_discard_range(MigrationIncomingState *mis, >> > >> > if ((start + length) <= rb->used_length) { >> > uint8_t *host_endaddr = host_startaddr + length; >> > - if ((uintptr_t)host_endaddr & (qemu_host_page_size - 1)) { >> > + if ((uintptr_t)host_endaddr & (rb->page_size - 1)) { >> > error_report("ram_discard_range: Unaligned end address: %p", >> > host_endaddr); >> > goto err; >> > } >> > - errno = ENOTSUP; >> > + errno = ENOTSUP; /* If we are missing MADVISE etc */ >> > + >> > + if (rb->page_size == qemu_host_page_size) { >> > #if defined(CONFIG_MADVISE) >> > - ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED); >> > + ret = qemu_madvise(host_startaddr, length, >> > QEMU_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) { >> > error_report("ram_discard_range: Failed to discard range " >> > "%s:%" PRIx64 " +%zx (%d)", >> >> Can we move this to qemu-posix or similar? >> qemu_punch_hole() or similar and just put all the magic there? > > I'm trying but it's tricky. > The problem is that: > a) To be able to tell which you need you need the pagesize of the > area > b) Then you need the fd if it is a hugepage > (You can get (a) from (b) by a syscall we already do once) > c) If it's normal RAM you need the memory address but... > d) If it's a hugepage you need the offset in the file > > which is a mess; so you either have to pass all those parameters, > or end up passing a RAMBlock* which doesn't feel like it should > make its way into any of the os-* files. > > I could move it to exec.c that already has some ifdef on OSs; > what do you think? > > Dave > >> For the rest, I am ok with it. > -- > Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK