https://projects.osmocom.org/https://projects.osmocom.org/favicon.ico?16647414092018-02-27T21:13:12ZOpen Source Mobile CommunicationsOsmoPCU - Bug #3013: regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'https://projects.osmocom.org/issues/3013?journal_id=79072018-02-27T21:13:12Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>Tried to revert the commit in question (with some conflict resolution) but it's still broken after that.<br />Note that the immediate parent commit of above regression is "Rewrite EGPRS Packet Uplink Assignment", which does sound similar. I haven't tested EGPRS.</p>
<p>I also notice that the commit in question says the rationale is to "simplify the code", yet the test expectations are modified along with it, particularly message octets. I would have expected code refactoring to not yield any PDU changes.</p>
<p>Short of understanding what exactly is going wrong, it seems that we need to "start over" from 2141962baf95bfaf11f19dacd59f7b8ac8d49ca3, cherry-picking commits that seem independent from the regression, and see if we can get osmo-pcu stable again that way. After that, we can re-evaluate the commits introducing the regression.</p>
<p>Unless of course someone is apt enough to fully understand the failure right now.</p> OsmoPCU - Bug #3013: regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'https://projects.osmocom.org/issues/3013?journal_id=79092018-02-27T21:55:48Zneelsnhofmeyr@sysmocom.de
<ul></ul><p>I've found a reasonably small set of commits to revert painlessly that renders osmo-pcu usable again:</p>
<p><a class="external" href="https://gerrit.osmocom.org/#/q/status:open+project:osmo-pcu+branch:master+topic:fix_regression">https://gerrit.osmocom.org/#/q/status:open+project:osmo-pcu+branch:master+topic:fix_regression</a></p>
<p>=</p>
<p><a class="external" href="https://gerrit.osmocom.org/6976">https://gerrit.osmocom.org/6976</a> Revert "Use Timing Advance Index in UL assignments" <br /><a class="external" href="https://gerrit.osmocom.org/6977">https://gerrit.osmocom.org/6977</a> Revert "Rewrite Packet Uplink Assignment" <br /><a class="external" href="https://gerrit.osmocom.org/6978">https://gerrit.osmocom.org/6978</a> Revert "Rewrite Packet Downlink Assignment" <br /><a class="external" href="https://gerrit.osmocom.org/6979">https://gerrit.osmocom.org/6979</a> Revert "Rewrite EGPRS Packet Uplink Assignment"</p>
<p>I'm creating a new ticket that asks for re-adding these patches: <a class="issue tracker-2 status-3 priority-2 priority-default closed" title="Feature: fix re-apply patches reverted by #3013, related: UL and DL packet assignment, and Timing Advance (Resolved)" href="https://projects.osmocom.org/issues/3014">#3014</a> ... and (almost) closing this one.</p> OsmoPCU - Bug #3013: regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'https://projects.osmocom.org/issues/3013?journal_id=79102018-02-27T21:56:03Zneelsnhofmeyr@sysmocom.de
<ul><li><strong>Status</strong> changed from <i>New</i> to <i>In Progress</i></li><li><strong>Assignee</strong> set to <i>neels</i></li><li><strong>% Done</strong> changed from <i>0</i> to <i>90</i></li></ul> OsmoPCU - Bug #3013: regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'https://projects.osmocom.org/issues/3013?journal_id=79142018-02-27T22:05:36Zneelsnhofmeyr@sysmocom.de
<ul><li><strong>Related to</strong> <i><a class="issue tracker-2 status-3 priority-2 priority-default closed" href="/issues/3014">Feature #3014</a>: fix re-apply patches reverted by #3013, related: UL and DL packet assignment, and Timing Advance</i> added</li></ul> OsmoPCU - Bug #3013: regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'https://projects.osmocom.org/issues/3013?journal_id=79152018-02-28T00:17:25Zneelsnhofmeyr@sysmocom.de
<ul><li><strong>File</strong> <a href="/attachments/2978">os3013_gprs_works__bts_master__pcu_neels-fix_regression-414fcbb0.pcapng</a> <a class="icon-only icon-download" title="Download" href="/attachments/download/2978/os3013_gprs_works__bts_master__pcu_neels-fix_regression-414fcbb0.pcapng">os3013_gprs_works__bts_master__pcu_neels-fix_regression-414fcbb0.pcapng</a> added</li><li><strong>File</strong> <a href="/attachments/2980">os3013_gprs_completely_unusable_1__bts_master__pcu_master_0.4.0.97-731e.pcapng</a> <a class="icon-only icon-download" title="Download" href="/attachments/download/2980/os3013_gprs_completely_unusable_1__bts_master__pcu_master_0.4.0.97-731e.pcapng">os3013_gprs_completely_unusable_1__bts_master__pcu_master_0.4.0.97-731e.pcapng</a> added</li><li><strong>File</strong> <a href="/attachments/2981">os3013_gprs_almost_completely_unusable_2__bts_master__pcu_master_0.4.0.97-731e.pcapng</a> <a class="icon-only icon-download" title="Download" href="/attachments/download/2981/os3013_gprs_almost_completely_unusable_2__bts_master__pcu_master_0.4.0.97-731e.pcapng">os3013_gprs_almost_completely_unusable_2__bts_master__pcu_master_0.4.0.97-731e.pcapng</a> added</li></ul><p>attaching pcaps.</p>
<p>Enabling too much GSMTAP made the PCU unusable, I have in the end enabled these few. I hope it is sufficient. Let me know if specific logs / gsmtaps should be added and I can easily do new traces.</p> OsmoPCU - Bug #3013: regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'https://projects.osmocom.org/issues/3013?journal_id=79162018-02-28T09:37:04Zlaforge
<ul></ul><blockquote>
<p>Enabling too much GSMTAP made the PCU unusable</p>
</blockquote>
<p>Yes, that's expectedm and this is why running OsmoPCU on sysmobts-1xxx for R&D is not the best possible setup. There's simply not a lot of spare CPU cycles for additional debugging/logging in the code.</p>
<p>I suggest PCU development/debugging is primarily done on a different hardware platform, Either with osmo-bts-trx + osmo-pcu on a normal x86 PC, or e.g. on a sysmobts-2100 which has <strong>much</strong> more CPU and a PHY very similar to the 1002.</p> OsmoPCU - Bug #3013: regression: GPRS fatally unresponsive since commit 'Rewrite Packet Downlink Assignment'https://projects.osmocom.org/issues/3013?journal_id=88232018-04-11T12:28:53Zneelsnhofmeyr@sysmocom.de
<ul><li><strong>Status</strong> changed from <i>In Progress</i> to <i>Resolved</i></li><li><strong>% Done</strong> changed from <i>90</i> to <i>100</i></li></ul><p>The reverts are merged, checking why the patches fail and re-committing them is tracked in <a class="issue tracker-2 status-3 priority-2 priority-default closed" title="Feature: fix re-apply patches reverted by #3013, related: UL and DL packet assignment, and Timing Advance (Resolved)" href="https://projects.osmocom.org/issues/3014">#3014</a></p>