Bug 483445
Summary: | Packets Loss with Netdump | ||
---|---|---|---|
Product: | Red Hat Enterprise Linux 4 | Reporter: | Qian Cai <qcai> |
Component: | kernel | Assignee: | Neil Horman <nhorman> |
Status: | CLOSED NOTABUG | QA Contact: | Martin Jenner <mjenner> |
Severity: | medium | Docs Contact: | |
Priority: | low | ||
Version: | 4.8 | CC: | nhorman |
Target Milestone: | rc | ||
Target Release: | --- | ||
Hardware: | All | ||
OS: | Linux | ||
Whiteboard: | |||
Fixed In Version: | Doc Type: | Bug Fix | |
Doc Text: | Story Points: | --- | |
Clone Of: | Environment: | ||
Last Closed: | 2009-02-01 19:09:23 UTC | Type: | --- |
Regression: | --- | Mount Type: | --- |
Documentation: | --- | CRM: | |
Verified Versions: | Category: | --- | |
oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
Cloudforms Team: | --- | Target Upstream Version: | |
Embargoed: |
Description
Qian Cai
2009-02-01 12:28:30 UTC
This isn't a bug, you're exercizing the pessimal case of netpoll. In the prior bug that you mention, we found a problem wherein there was access to shared data from multiple contexts causing a panic. The fix for that was to enforce the needed mutual exclusion between those contexts. Since one of the contexts was the nominal receive fast path (net_rx_action), netpoll now (correctly) blocks receive operations while calling the poll_controller/poll methods of a driver. doing this puts us at risk for frame loss. By sending multiple sysrq-t's, you effectively create multiple windows of time where we can't rx frames, leading to overflow and frame drops. This is working as it should. |