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Thu, 4 May 2023 16:58:42 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.42]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 32506492C13; Thu, 4 May 2023 16:58:41 +0000 (UTC) Date: Thu, 4 May 2023 17:58:39 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Juan Quintela Cc: qemu-devel@nongnu.org, qemu-block@nongnu.org, Stefan Hajnoczi , Leonardo Bras , Fam Zheng , Peter Xu Subject: Re: [PATCH 9/9] qemu-file: Account for rate_limit usage on qemu_fflush() Message-ID: References: <20230504113841.23130-1-quintela@redhat.com> <20230504113841.23130-10-quintela@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230504113841.23130-10-quintela@redhat.com> User-Agent: Mutt/2.2.9 (2022-11-12) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -22 X-Spam_score: -2.3 X-Spam_bar: -- X-Spam_report: (-2.3 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.161, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, May 04, 2023 at 01:38:41PM +0200, Juan Quintela wrote: > That is the moment we know we have transferred something. > > Signed-off-by: Juan Quintela > --- > migration/qemu-file.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c > index ddebfac847..309b4c56f4 100644 > --- a/migration/qemu-file.c > +++ b/migration/qemu-file.c > @@ -300,7 +300,9 @@ void qemu_fflush(QEMUFile *f) > &local_error) < 0) { > qemu_file_set_error_obj(f, -EIO, local_error); > } else { > - f->total_transferred += iov_size(f->iov, f->iovcnt); > + uint64_t size = iov_size(f->iov, f->iovcnt); > + qemu_file_acct_rate_limit(f, size); > + f->total_transferred += size; > } > > qemu_iovec_release_ram(f); > @@ -527,7 +529,6 @@ void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, size_t size, > return; > } > > - f->rate_limit_used += size; > add_to_iovec(f, buf, size, may_free); > } > > @@ -545,7 +546,6 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size) > l = size; > } > memcpy(f->buf + f->buf_index, buf, l); > - f->rate_limit_used += l; > add_buf_to_iovec(f, l); > if (qemu_file_get_error(f)) { > break; > @@ -562,7 +562,6 @@ void qemu_put_byte(QEMUFile *f, int v) > } > > f->buf[f->buf_index] = v; > - f->rate_limit_used++; > add_buf_to_iovec(f, 1); > } This has a slight semantic behavioural change. By accounting for rate limit in the qemu_put functions, we ensure that we stop growing the iovec when rate limiting activates. If we only apply rate limit in the the flush function, that will let the f->iov continue to accumulate buffers, while we have rate limited the actual transfer. This makes me uneasy - it feels like a bad idea to continue to accumulate buffers if we're not ready to send them With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|