From: Gerrit Renker Date: Fri, 20 Jul 2007 17:27:37 +0000 Subject: Performance with entirely unpatched 2.6.22 kernel Message-Id: <200707201827.37769@strip-the-willow> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: quoted-printable To: dccp@vger.kernel.org I haven't been able to get to the ground of the problem why the performance= =20 is currently so bad, but on a clean, unpatched 2.6.22 kernel (from netdev), I already get packet loss reports on a lossless link (see below).=20 Applying the test-tree patches on top leads to reported loss rates of up to 10 percent. If that happens in the bandwidth-restricted link, then no wonder the performance drops down.=20 Will investigate further, but DCCP may not be the only corner to look for. In any case, I find the many negative (late) delays below also suspicious. Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_parse_options: client(f484d030),= LOSS_EVENT_RATEB94967295 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_update_x: X_prevt98324, X_now=14= 996648, X_calc=3D0, X_recv=11887895 Jul 20 18:09:41 gerrit kernel: ccid3_update_send_interval: t_ipi=94, deltaG= , s=1415, X=14996648 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_packet_recv: client(f484d030), R= TT=1827us (sample=1803us), s=1415, p=3D0, X_calc0, X_recv=11887895, X=14996= 648 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-19169 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-19108 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-19047 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18984 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18921 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18857 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18798 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18735 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18673 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18610 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18548 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18487 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18423 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18389 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18327 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18264 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-18200 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_senlay=3D-2887 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2659 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2455 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2255 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2050 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-1844 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_parse_options: client(f484d030),= RECEIVE_RATE=1420590 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_parse_options: client(f484d030),= LOSS_EVENT_RATE1 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_update_x: X_prevY08095, X_now(41= 180, X_calcU50695, X_recv=1420590 Jul 20 18:09:41 gerrit kernel: ccid3_update_send_interval: t_ipiI8, delta$9= , s=1415, X(41180 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_packet_recv: client(f484d030), R= TT=1339us (sample 70us), s=1415, p2258, X_c alcU50695, X_recv=1420590, X(41180 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-3872 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-3460 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2995 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2612 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2148 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-1682 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-1215 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-749 Jul 20 18:09:41 gerrit kernel: ccid3_hc_tx_send_packet: delay=3D-2610