From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41462) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e1xoa-0003kf-07 for qemu-devel@nongnu.org; Tue, 10 Oct 2017 12:55:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e1xoW-0006eU-Uf for qemu-devel@nongnu.org; Tue, 10 Oct 2017 12:55:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48554) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e1xoW-0006dx-KP for qemu-devel@nongnu.org; Tue, 10 Oct 2017 12:55:28 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 70AF67E440 for ; Tue, 10 Oct 2017 16:55:27 +0000 (UTC) References: <20171010154328.8419-1-berrange@redhat.com> <20171010154328.8419-3-berrange@redhat.com> From: Eric Blake Message-ID: <5622c2ab-caa8-3c46-0926-c46218a3d179@redhat.com> Date: Tue, 10 Oct 2017 11:55:25 -0500 MIME-Version: 1.0 In-Reply-To: <20171010154328.8419-3-berrange@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="SptGgNPBAiuI2BJUdrcvDKA1MLsubUUXm" Subject: Re: [Qemu-devel] [PATCH v1 2/7] io: simplify websocket ping reply handling List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" , qemu-devel@nongnu.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --SptGgNPBAiuI2BJUdrcvDKA1MLsubUUXm From: Eric Blake To: "Daniel P. Berrange" , qemu-devel@nongnu.org Message-ID: <5622c2ab-caa8-3c46-0926-c46218a3d179@redhat.com> Subject: Re: [Qemu-devel] [PATCH v1 2/7] io: simplify websocket ping reply handling References: <20171010154328.8419-1-berrange@redhat.com> <20171010154328.8419-3-berrange@redhat.com> In-Reply-To: <20171010154328.8419-3-berrange@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 10/10/2017 10:43 AM, Daniel P. Berrange wrote: > We must ensure we don't get flooded with ping replies if the outbound > channel is slow. Currently we do this by keeping the ping reply in a > separate temporary buffer and only writing it if the encoutput buffer > is completely empty. This is overly pessimistic, as it is reasonable > to add a ping reply to the encoutput buffer even if it has previous > data in it, as long as that previous data doesn't include a ping > reply. >=20 > To track this better, put the ping reply directly into the encoutput > buffer, and then record the size of encoutput at this time in > ping_remain. As we write encoutput to the underlying channel, we > can decrement the ping_remain counter. Once it hits zero, we can > accept further ping replies for transmission. >=20 > Signed-off-by: Daniel P. Berrange > --- > include/io/channel-websock.h | 2 +- > io/channel-websock.c | 28 +++++++++++++++------------- > 2 files changed, 16 insertions(+), 14 deletions(-) >=20 > +++ b/io/channel-websock.c > @@ -825,11 +825,14 @@ static int qio_channel_websock_decode_payload(QIO= ChannelWebsock *ioc, > } > return -1; > } else if (ioc->opcode =3D=3D QIO_CHANNEL_WEBSOCK_OPCODE_PING) { > - /* ping frames produce an immediate reply */ > - buffer_reset(&ioc->ping_reply); > - qio_channel_websock_encode_buffer( > - ioc, &ioc->ping_reply, QIO_CHANNEL_WEBSOCK_OPCODE_PONG, > - &ioc->encinput); > + /* ping frames produce an immediate reply, as long as we've no= t still > + * got a previous ping queued, in which case we drop the new p= ong */ Wouldn't that be a 'previous pong queued'? > + if (ioc->ping_remain =3D=3D 0) { > + qio_channel_websock_encode_buffer( > + ioc, &ioc->encoutput, QIO_CHANNEL_WEBSOCK_OPCODE_PONG,= > + &ioc->encinput); > + ioc->ping_remain =3D ioc->encoutput.offset; > + } But if you change the comment, then naming the variable pong_remain may make more sense. But naming is a bikeshed issue, so either way, Reviewed-by: Eric Blake --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org --SptGgNPBAiuI2BJUdrcvDKA1MLsubUUXm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEzBAEBCAAdFiEEccLMIrHEYCkn0vOqp6FrSiUnQ2oFAlnc+30ACgkQp6FrSiUn Q2qtLQf/cedSay8bMR7PqrOBTxliKdr0OCMA2/pqvkDfnrlbIvW0gSUi09IAJWMS WzqexnfUOeioozsPZbt1ZnM1dBY3GBinGYkz0AEOTTTosQ1ObhUZ5d7pMhk1DmrH xhbuuEMxWwqhPAmAm2OW3kkPKiSZTZpIbPwNEuBvCp8vZUsw/pYD++aiNoFmbxBb N53+ABg6GXjKg7MFpEE3+g5AgSdkUTQ4Ysb+Ng+dbtb6eYueISJ4PeSSbUOrwB/n khnkbjS6R1oCJFUVE+rGGNilefXY7QiDmTEQXAFdHqubN6YaQAgRAzYRErRxRVZ0 VS02bnnKjQ7hxAyXHkb7eYHQb+x2xg== =TuLM -----END PGP SIGNATURE----- --SptGgNPBAiuI2BJUdrcvDKA1MLsubUUXm--