Bug 15487
| Summary: | System hangs during retransmit of TCP ACK or SACK | ||
|---|---|---|---|
| Product: | Networking | Reporter: | Yuriy Yevtukhov (yuriy) |
| Component: | IPV4 | Assignee: | Stephen Hemminger (stephen) |
| Status: | RESOLVED DUPLICATE | ||
| Severity: | high | ||
| Priority: | P1 | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Kernel Version: | 2.6.32.8 | Subsystem: | |
| Regression: | No | Bisected commit-id: | |
| Attachments: |
Crash dump
custom kernel config |
||
Created attachment 25420 [details]
custom kernel config
Checked something. It seems that net.ipv4.tcp_sack=1 enables this problem. (In reply to comment #2) > Checked something. It seems that > net.ipv4.tcp_sack=1 > enables this problem. I meant together with other my tuning. As I never noticed this problem on server with net.ipv4.tcp_rmem=4096 87380 2097152 net.ipv4.tcp_wmem=4096 131072 2097152 net.ipv4.tcp_fin_timeout=15 net.ipv4.tcp_syn_retries=5 net.ipv4.tcp_synack_retries=2 net.ipv4.ip_local_port_range=4096 65000 net.ipv4.tcp_sack=0 net.ipv4.tcp_timestamps=1 net.ipv4.tcp_retries1=2 Or may be these tunings are unrelated. |
Created attachment 25419 [details] Crash dump System (highly loaded web server) accidentially hangs after several days after outputting crash dump. No reaction to keyboard or records in system logs. By this reason only last part of crash dump is accessible, screen copy is in attachment. Problem was noticed in kernel 2.6.31.6. Then upgrade was made to 2.6.32.8. Problem seems to be connected with my tunings of system variables. Here they are net.ipv4.tcp_syncookies=1 net.ipv4.tcp_max_syn_backlog=8192 net.core.rmem_max=4194304 net.core.wmem_max=4194304 net.ipv4.tcp_mem=786432 1048576 1572864 net.ipv4.tcp_rmem=4096 87380 1048576 net.ipv4.tcp_wmem=4096 32768 1048576 net.ipv4.tcp_orphan_retries=4 net.ipv4.tcp_fin_timeout=15 net.ipv4.tcp_syn_retries=5 net.ipv4.tcp_synack_retries=2 net.ipv4.tcp_sack=1 net.ipv4.tcp_timestamps=1 net.ipv4.tcp_retries1=3 Other changed values unrelated to TCP. Problem noticed on different hardware (Multiple Xeons with Intel's chipset and network cards, Multiple Opterons with nvidia's netword cards) with 16-32GB of memory. Never noticed before providing specified sysctl values.