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Re: [Qemu-devel] [PATCH] migration: ram_handle_compressed
From: |
Isaku Yamahata |
Subject: |
Re: [Qemu-devel] [PATCH] migration: ram_handle_compressed |
Date: |
Fri, 20 Sep 2013 16:43:00 +0900 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Wed, Sep 18, 2013 at 02:08:40PM +0200, Juan Quintela wrote:
> Isaku Yamahata <address@hidden> wrote:
> > ram_handle_compressed() should be aware size > TARGET_PAGE_SIZE
> > migration-rdma can call it with larger size.
> >
> > Signed-off-by: Isaku Yamahata <address@hidden>
> > ---
> > arch_init.c | 21 ++++++++++++++-------
> > 1 file changed, 14 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch_init.c b/arch_init.c
> > index e47e139..64c81b0 100644
> > --- a/arch_init.c
> > +++ b/arch_init.c
> > @@ -844,15 +844,22 @@ static inline void *host_from_stream_offset(QEMUFile
> > *f,
> > */
> > void ram_handle_compressed(void *host, uint8_t ch, uint64_t size)
> > {
> > - if (ch != 0 || !is_zero_page(host)) {
> > - memset(host, ch, size);
>
> I assume that size is always a multiple of pagesize, right?
Right. The issues is that is_zero_page() checks only first page.
The following page needs to be checked.
>
> > + uint64_t pagesize = getpagesize();
> > + while (size > 0) {
> > + uint64_t length = MIN(pagesize, size);
> > +
> > + if (ch !=0 || buffer_find_nonzero_offset(host, length) != length) {
>
> This is a different optimization, we were't doing this before.
Okay, I'll drop loop and use size.
thanks,
> > + memset(host, ch, length);
> > #ifndef _WIN32
> > - if (ch == 0 &&
> > - (!kvm_enabled() || kvm_has_sync_mmu()) &&
> > - getpagesize() <= TARGET_PAGE_SIZE) {
> > - qemu_madvise(host, TARGET_PAGE_SIZE, QEMU_MADV_DONTNEED);
> > - }
> > + if (ch == 0 &&
> > + (!kvm_enabled() || kvm_has_sync_mmu()) && pagesize <=
> > length) {
> > + qemu_madvise(host, size, QEMU_MADV_DONTNEED);
>
> Here don't we need s/size/length/?
>
> > + }
> > #endif
> > + }
> > +
> > + size -= length;
> > + host += length;
> > }
> > }
>
--
yamahata