Re: [Qemu-devel] [PATCH 11/14] buffered_file: don't flush on put buffer

[Paolo Bonzini <pbonzini@redhat.com>]

Il 21/09/2012 16:08, Juan Quintela ha scritto:
> We call buffered_put_buffer with iothread held, and buffered_flush() does
> synchronous writes.  We only want to do the synchronous writes outside.
> 
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>  buffered_file.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/buffered_file.c b/buffered_file.c
> index f4a788d..929b911 100644
> --- a/buffered_file.c
> +++ b/buffered_file.c
> @@ -107,12 +107,6 @@ static int buffered_put_buffer(void *opaque, const uint8_t *buf, int64_t pos, in
>          buffered_append(s, buf, size);
>      }
> 
> -    error = buffered_flush(s);
> -    if (error < 0) {
> -        DPRINTF("buffered flush error. bailing: %s\n", strerror(-error));
> -        return error;
> -    }
> -
>      return size;
>  }
> 

This means that the buffer can grow to up to s->xfer_limit bytes.
Perhaps you want to make the granularity (currently fixed to 100ms) a
bit smaller, like 20-30 ms, if the bandwidth limit grows above say 100
MB/sec?  This can be done on top of this series however.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>