Servers become sluggish, experience latency in running commands, and generally become less responsive

Issue

• General responsiveness of the system goes down at times
• Latency increases for all commands and services with no apparent cause
• Low-to-moderate load followed by sudden extreme load visible in sar
• System load driven up due to processes piling up waiting for NFS workloads to complete (if applicable)
• Java applications appear slow
• Rebooting the system brings back better performance

Various performance issues may be observed, including /var/log/messages logging with entries similar to this, which appear to be a network interface or kernel issue:

Jun  6 21:09:57 amnesiac kernel: NETDEV WATCHDOG: eth0 (tg3): transmit queue 0 timed out
Jun  6 21:09:57 amnesiac kernel: Call Trace:
Jun  6 21:09:57 amnesiac kernel: <IRQ>  [<ffffffff8106e3e7>] ? warn_slowpath_common+0x87/0xc0
Jun  6 21:09:57 amnesiac kernel: [<ffffffff8106e4d6>] ? warn_slowpath_fmt+0x46/0x50
Jun  6 21:09:57 amnesiac kernel: [<ffffffff8146800d>] ? dev_watchdog+0x26d/0x280
Jun  6 21:09:57 amnesiac kernel: [<ffffffff81090e8d>] ? insert_work+0x6d/0xb0
Jun  6 21:09:57 amnesiac kernel: [<ffffffff81080d25>] ? internal_add_timer+0xb5/0x110
Jun  6 21:09:57 amnesiac kernel: [<ffffffff81467da0>] ? dev_watchdog+0x0/0x280
Jun  6 21:09:57 amnesiac kernel: [<ffffffff81081937>] ? run_timer_softirq+0x197/0x340
Jun  6 21:09:57 amnesiac kernel: [<ffffffff810a8060>] ? tick_sched_timer+0x0/0xc0
Jun  6 21:09:57 amnesiac kernel: [<ffffffff8102ea2d>] ? lapic_next_event+0x1d/0x30
Jun  6 21:09:57 amnesiac kernel: [<ffffffff810770b1>] ? __do_softirq+0xc1/0x1e0
Jun  6 21:09:57 amnesiac kernel: [<ffffffff8109b87b>] ? hrtimer_interrupt+0x14b/0x260
Jun  6 21:09:57 amnesiac kernel: [<ffffffff8100c1cc>] ? call_softirq+0x1c/0x30
Jun  6 21:09:57 amnesiac kernel: [<ffffffff8100de05>] ? do_softirq+0x65/0xa0
Jun  6 21:09:57 amnesiac kernel: [<ffffffff81076e95>] ? irq_exit+0x85/0x90
Jun  6 21:09:57 amnesiac kernel: [<ffffffff81517820>] ? smp_apic_timer_interrupt+0x70/0x9b
Jun  6 21:09:57 amnesiac kernel: [<ffffffff8100bb93>] ? apic_timer_interrupt+0x13/0x20
Jun  6 21:09:57 amnesiac kernel: <EOI> 
Jun  6 21:09:57 amnesiac kernel: ---[ end trace 644b4a60cea93ef2 ]---
Jun  6 21:09:57 amnesiac kernel: tg3 0000:01:00.0: eth0: transmit timed out, resetting