| Message ID | 1365420597-5506-5-git-send-email-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
Paolo Bonzini <pbonzini@redhat.com> wrote: > Check f->iovcnt in add_to_iovec, f->buf_index in qemu_put_buffer/byte. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > savevm.c | 22 +++++++++------------- > 1 file changed, 9 insertions(+), 13 deletions(-) > > diff --git a/savevm.c b/savevm.c > index a2f6bc0..63f4c82 100644 > --- a/savevm.c > +++ b/savevm.c > @@ -626,7 +626,7 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size) > f->iov[f->iovcnt++].iov_len = size; > } > > - if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) { > + if (f->iovcnt >= MAX_IOV_SIZE) { > qemu_fflush(f); > } > } > @@ -662,12 +662,10 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) > f->bytes_xfer += size; > if (f->ops->writev_buffer) { > add_to_iovec(f, f->buf + f->buf_index, l); > - f->buf_index += l; > - } else { > - f->buf_index += l; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > - } > + } > + f->buf_index += l; > + if (f->buf_index == IO_BUF_SIZE) { > + qemu_fflush(f); > } > if (qemu_file_get_error(f)) { > break; > @@ -687,12 +685,10 @@ void qemu_put_byte(QEMUFile *f, int v) > f->bytes_xfer++; > if (f->ops->writev_buffer) { > add_to_iovec(f, f->buf + f->buf_index, 1); > - f->buf_index++; > - } else { > - f->buf_index++; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > - } > + } > + f->buf_index++; > + if (f->buf_index == IO_BUF_SIZE) { > + qemu_fflush(f); > } > } If you follow my advice of moving the call to add_to_iovec() you get this one simplified and only one place to do this. Thanks, Juan.
Il 09/04/2013 13:43, Juan Quintela ha scritto: >> > @@ -687,12 +685,10 @@ void qemu_put_byte(QEMUFile *f, int v) >> > f->bytes_xfer++; >> > if (f->ops->writev_buffer) { >> > add_to_iovec(f, f->buf + f->buf_index, 1); >> > - f->buf_index++; >> > - } else { >> > - f->buf_index++; >> > - if (f->buf_index == IO_BUF_SIZE) { >> > - qemu_fflush(f); >> > - } >> > + } >> > + f->buf_index++; >> > + if (f->buf_index == IO_BUF_SIZE) { >> > + qemu_fflush(f); >> > } >> > } > If you follow my advice of moving the call to add_to_iovec() you get > this one simplified and only one place to do this. Moving what call? The apparent complication is because the old logic was a bit more involute than necessary. If you look at the code after the patches, not the patches themselves, you'll see for yourself. The logic now is: add byte if using iovs add byte to iov list if buffer full flush add_to_iovec has no business checking the buffer. Why should qemu_put_buffer_async() check the buffer? The duplication between qemu_put_byte and qemu_put_buffer is a different topic. I think it's acceptable in the name of performance, but perhaps you can just call qemu_put_buffer(f, &c, 1). Paolo
Paolo Bonzini <pbonzini@redhat.com> wrote: > Il 09/04/2013 13:43, Juan Quintela ha scritto: >>> > @@ -687,12 +685,10 @@ void qemu_put_byte(QEMUFile *f, int v) >>> > f->bytes_xfer++; >>> > if (f->ops->writev_buffer) { >>> > add_to_iovec(f, f->buf + f->buf_index, 1); >>> > - f->buf_index++; >>> > - } else { >>> > - f->buf_index++; >>> > - if (f->buf_index == IO_BUF_SIZE) { >>> > - qemu_fflush(f); >>> > - } >>> > + } >>> > + f->buf_index++; >>> > + if (f->buf_index == IO_BUF_SIZE) { >>> > + qemu_fflush(f); >>> > } >>> > } >> If you follow my advice of moving the call to add_to_iovec() you get >> this one simplified and only one place to do this. > > Moving what call? The apparent complication is because the old logic > was a bit more involute than necessary. If you look at the code after > the patches, not the patches themselves, you'll see for yourself. > > The logic now is: > > add byte > if using iovs > add byte to iov list > if buffer full > flush > > add_to_iovec has no business checking the buffer. Why should > qemu_put_buffer_async() check the buffer? We can rename the function. I agree with that. > > The duplication between qemu_put_byte and qemu_put_buffer is a different > topic. I think it's acceptable in the name of performance, but perhaps > you can just call qemu_put_buffer(f, &c, 1). Right now, it is important because all the integer types are sent as callas to qemu_put_byte(), but Orit had a patch to rewrote those using qemu_put_buffer() dirrectly, and then we don't use so many qemu_put_byte()'s anymore. Later, Juan.
On 04/09/2013 02:53 PM, Paolo Bonzini wrote: > Il 09/04/2013 13:43, Juan Quintela ha scritto: >>>> @@ -687,12 +685,10 @@ void qemu_put_byte(QEMUFile *f, int v) >>>> f->bytes_xfer++; >>>> if (f->ops->writev_buffer) { >>>> add_to_iovec(f, f->buf + f->buf_index, 1); >>>> - f->buf_index++; >>>> - } else { >>>> - f->buf_index++; >>>> - if (f->buf_index == IO_BUF_SIZE) { >>>> - qemu_fflush(f); >>>> - } >>>> + } >>>> + f->buf_index++; >>>> + if (f->buf_index == IO_BUF_SIZE) { >>>> + qemu_fflush(f); >>>> } >>>> } >> If you follow my advice of moving the call to add_to_iovec() you get >> this one simplified and only one place to do this. > > Moving what call? The apparent complication is because the old logic > was a bit more involute than necessary. If you look at the code after > the patches, not the patches themselves, you'll see for yourself. > > The logic now is: > > add byte > if using iovs > add byte to iov list > if buffer full > flush > > add_to_iovec has no business checking the buffer. Why should > qemu_put_buffer_async() check the buffer? > > The duplication between qemu_put_byte and qemu_put_buffer is a different > topic. I think it's acceptable in the name of performance, but perhaps > you can just call qemu_put_buffer(f, &c, 1). I thought about it too, we can keep the optimization by checking the size Orit > > Paolo >
diff --git a/savevm.c b/savevm.c index a2f6bc0..63f4c82 100644 --- a/savevm.c +++ b/savevm.c @@ -626,7 +626,7 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size) f->iov[f->iovcnt++].iov_len = size; } - if (f->buf_index >= IO_BUF_SIZE || f->iovcnt >= MAX_IOV_SIZE) { + if (f->iovcnt >= MAX_IOV_SIZE) { qemu_fflush(f); } } @@ -662,12 +662,10 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size) f->bytes_xfer += size; if (f->ops->writev_buffer) { add_to_iovec(f, f->buf + f->buf_index, l); - f->buf_index += l; - } else { - f->buf_index += l; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + } + f->buf_index += l; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); } if (qemu_file_get_error(f)) { break; @@ -687,12 +685,10 @@ void qemu_put_byte(QEMUFile *f, int v) f->bytes_xfer++; if (f->ops->writev_buffer) { add_to_iovec(f, f->buf + f->buf_index, 1); - f->buf_index++; - } else { - f->buf_index++; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + } + f->buf_index++; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); } }
Check f->iovcnt in add_to_iovec, f->buf_index in qemu_put_buffer/byte. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- savevm.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-)