Messages in this thread | | | Date | Wed, 5 Jan 2005 00:07:33 +0100 | From | Marek Habersack <> | Subject | Re: Very high load on P4 machines with 2.4.28 |
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On Tue, Jan 04, 2005 at 11:03:13PM +0100, Willy Tarreau scribbled: > Hi, > > On Tue, Jan 04, 2005 at 08:56:36PM +0100, Marek Habersack wrote: > (...) > > equipped with 2.6Ghz P4 CPUs, 1Gb of ram, 2-4gb of swap, the kernel config > > is attached. The machines have normal load averages hovering not higher than > > 7.0, depending on the time of the day etc. Two of the machines run 2.4.25, > > one 2.4.27 and they work fine. When booted with 2.4.28, though (compiled > > with Debian's gcc 2.3.5, with p3 or p4 CPU selected in the config), the load > > is climbing very fast and hovers around a value 3-4 times higher than with > > the older kernels. Booted back in the old kernel, the load comes to its > > usual level. The logs suggest nothing, no errors, nothing unusual is > > happening. > > > > Has anyone had similar problems with 2.4.28 in an environment resembling the > > above? Could it be a problem with highmem i/o? > > Never encountered yet ! Could you provide some indications about the type of > work (I/O, network, CPU, scripts execution, #of processes, etc...) ? Of course. Here's some information:
the machines (with exception of one) are virtual hosting servers running apache with a lot of customer-provided perl scripts, php code, mysql (quite heavily used). The bandwidth used ranges from 4Mbit/s (the non-virtual box) to 24Mbit/s. The number of processes ranges from ~300 to ~600. Interestingly enough, the machine with the highest load average is the one generating 4Mbit/s and the one with 24Mbit/s has the smallest load average value. The latter also suffers from the biggest loadavg increase. All of the virtual machines have iptables accounting chains for each configured IP (there are between 62 IP numbers on one and 32 on the other). The virtual boxes have two 80GB SATA drives raided with softraid. The non-virtual box has a single IDE drive, no raid.
Some diagnostics (virtuals running 2.4.25 with ow1, non-virtual 2.4.27 with ow1):
(virtual #1) # vmstat procs -----------memory---------- ---swap-- -----io---- --system------cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 108364 33376 3032 382452 1 1 85 107 79 76 42 7 52 0
# iostat avg-cpu: %user %nice %sys %iowait %idle 41.86 0.00 6.63 0.00 51.51
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn dev8-0 44.33 91.04 761.64 32859202 274901552 dev8-1 44.07 88.28 759.27 31863034 274048056
# cat /proc/interrupts CPU0 0: 36164314 XT-PIC timer 1: 2 XT-PIC keyboard 2: 0 XT-PIC cascade 4: 5 XT-PIC serial 8: 4 XT-PIC rtc 10: 304927622 XT-PIC eth0 12: 786373 XT-PIC eth1 14: 31209236 XT-PIC libata 15: 1 XT-PIC ide1 NMI: 0 ERR: 0
(virtual #2, the 24Mbit/s one) # vmstat procs -----------memory---------- ---swap-- -----io---- --system------cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 5 3 172448 13084 1208 304048 4 4 90 50 109 117 19 8 73 0
# iostat avg-cpu: %user %nice %sys %iowait %idle 18.76 0.00 7.98 0.00 73.26
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn dev8-0 28.66 465.98 323.12 168199261 116634204 dev8-1 28.26 458.50 314.57 165501660 113547124
# cat /proc/interrupts CPU0 0: 36164279 XT-PIC timer 1: 2 XT-PIC keyboard 2: 0 XT-PIC cascade 4: 5 XT-PIC serial 8: 4 XT-PIC rtc 10: 713628758 XT-PIC eth0 12: 1452211 XT-PIC eth1 14: 20094643 XT-PIC libata 15: 1 XT-PIC ide1 NMI: 0 ERR: 0
(the non-virtual) # vmstat procs -----------memory---------- ---swap-- -----io---- --system------cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 60 0 70300 115960 0 369244 0 0 79 32 90 45 73 7 21 0
# iostat avg-cpu: %user %nice %sys %iowait %idle 72.64 0.03 6.63 0.00 20.71
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn dev3-0 7.62 54.77 91.76 19834569 33227488
# cat /proc/interrupts CPU0 0: 36284746 XT-PIC timer 1: 2 XT-PIC keyboard 2: 0 XT-PIC cascade 4: 6 XT-PIC serial 8: 4 XT-PIC rtc 10: 787346 XT-PIC eth1 11: 120939540 XT-PIC eth0 14: 2743009 XT-PIC ide0 15: 1069794 XT-PIC ide1 NMI: 0 ERR: 0
sar doesn't show anything interesting for any of the boxes. We tried to run 2.6.10 on the non-virtual box to see whether it could cope with its load problems, it crashed after one day with no trace in the logs as to what might have caused the problem (this box runs some software that's pretty bursty and CPU-intensive giving sometimes around 50-80 apache processes running at a time). One other interesting thing to note is that we have one other box with the similar configuration to the virtuals (also a virtual host) but it runs 2.4.28 with SMP+HT enabled - no load problems there at all. In the past we had a problem with P4 machines running very slowly when the kernel was compiled with the P4 CPU target, but it was on different hardware (an MSI mobo, the boxes above all have Supermicro mobos) and compiling the kernel with P3 CPU target helped with the slowness. That's why we tried the same "trick" here - but this time it didn't help. Let me know if you need more info,
thanks for your help, best regards
marek [unhandled content-type:application/pgp-signature] | |