We've just upgraded a few machines from squeeze to wheezy and have seen the described increase and significant spikes in load average. Our machines are VMs running apache with a homebrew module, handling around one thousand requests per second all the time.
This kernel has higher than expected load averages and random spikes into the
10s and 20s.
# dpkg -s linux-image-3.2.0-4-amd64
Package: linux-image-3.2.0-4-amd64
Status: install ok installed
Priority: optional
Section: kernel
Installed-Size: 105529
Maintainer: Debian Kernel Team <debian-ker...@lists.debian.org>
Architecture: amd64
Source: linux
Version: 3.2.46-1
Provides: linux-image, linux-modules-3.2.0-4-amd64
Depends: kmod | module-init-tools, linux-base (>= 3~), initramfs-tools (>=
0.99~) | linux-initramfs-tool
Pre-Depends: debconf | debconf-2.0
Recommends: firmware-linux-free (>= 3~)
Suggests: linux-doc-3.2, debian-kernel-handbook, grub-pc | extlinux | lilo
Breaks: at (<< 3.1.12-1+squeeze1), initramfs-tools (<< 0.99~)
Description: Linux 3.2 for 64-bit PCs
The Linux kernel 3.2 and modules for use on PCs with AMD64, Intel 64 or
VIA Nano processors.
.
This kernel also runs on a Xen hypervisor. It supports both privileged
(dom0) and unprivileged (domU) operation.
This kernel does not.
Load averages almost always stay in the 0.10 to 0.50 range.
# dpkg -s linux-image-2.6.32-5-amd64
Package: linux-image-2.6.32-5-amd64
Status: install ok installed
Priority: optional
Section: kernel
Installed-Size: 97560
Maintainer: Debian Kernel Team <debian-ker...@lists.debian.org>
Architecture: amd64
Source: linux-2.6
Version: 2.6.32-35
Provides: linux-image, linux-image-2.6, linux-modules-2.6.32-5-amd64
Depends: module-init-tools, linux-base (>= 2.6.32-35), initramfs-tools (>=
0.55) | linux-initramfs-tool
Pre-Depends: debconf | debconf-2.0
Recommends: firmware-linux-free (>= 2.6.32)
Suggests: linux-doc-2.6.32, grub | lilo (>= 22.8-8.2~)
Breaks: initramfs-tools (<< 0.55), lilo (<< 22.8-8.2~)
Description: Linux 2.6.32 for 64-bit PCs
The Linux kernel 2.6.32 and modules for use on PCs with AMD64 or Intel 64
processors.
.
This kernel also runs on a Xen hypervisor. It supports only unprivileged
(domU) operation.
I'll gladly try kernels in-between to help narrow down when the issue arose as
we can reboot whenever necessary.
I've been running the following for about an hour now, to grab 'top -b'
whenever the load average is high (2 or above).
# while :; do test $(uptime | sed -e 's/.*average://g' | awk '{print $1}' |
cut -d. -f1) -gt 2 && top -b -n 1 > top-$(date +%s); sleep 1; done
Attached are the top 15 lines of each top output, without apache2 in.
Naturally apache is the busiest process so a bit pointless including it.
# head -n 15 top-13753* | grep -v apache2 | gzip - > alltop.gz
--
Mike Williams
alltop.gz
Description: GNU Zip compressed data
