[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <80dcf47eb772c65a62652d7a56c8ed26@eikelenboom.it>
Date: Sat, 28 Nov 2015 16:47:43 +0100
From: Sander Eikelenboom <linux@...elenboom.it>
To: boris.ostrovsky@...cle.com, david.vrabel@...rix.com
Cc: linux-kernel@...r.kernel.org, xen-devel@...ts.xen.org
Subject: linux 4.4 Regression: 100% cpu usage on idle pv guest under Xen
with single vcpu.
Hi all,
I have just tested a 4.4-rc2 kernel (current linus tree) + the tip tree
pulled on top.
Running this kernel under Xen on PV-guests with multiple vcpus goes well
(on idle < 10% cpu usage),
but a guest with only a single vcpu doesn't idle at all, it seems a
kworker thread is stuck:
root 569 98.0 0.0 0 0 ? R 16:02 12:47
[kworker/0:1]
Running a 4.3 kernel works fine with a single vpcu, bisecting would
probably quite painful since there were some breakages this merge window
with respect to Xen pv-guests.
There are some differences in the diff's from booting a 4.3, 4.4-single,
4.4-multi cpu boot:
Between 4.3 and 4.4-single:
-NR_IRQS:4352 nr_irqs:32 16
+Using NULL legacy PIC
+NR_IRQS:4352 nr_irqs:32 0
-cpu 0 spinlock event irq 17
+cpu 0 spinlock event irq 1
and later on:
-hctosys: unable to open rtc device (rtc0)
+rtc_cmos rtc_cmos: hctosys: unable to read the hardware clock
+genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000
(rtc0)
+hvc_open: request_irq failed with rc -16.
+Warning: unable to open an initial console.
between 4.4-single and 4.4-multi:
Using NULL legacy PIC
-NR_IRQS:4352 nr_irqs:32 0
+NR_IRQS:4352 nr_irqs:48 0
and later on:
-rtc_cmos rtc_cmos: hctosys: unable to read the hardware clock
+hctosys: unable to open rtc device (rtc0)
-genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000
(rtc0)
-hvc_open: request_irq failed with rc -16.
-Warning: unable to open an initial console.
attached:
- dmesg with 4.3 kernel with 1 vcpu
- dmesg with 4.4 kernel with 1 vpcu
- dmesg with 4.4 kernel with 2 vpcus
- .config of the 4.4 kernel is attached.
--
Sander
View attachment "dotconfig" of type "text/plain" (105273 bytes)
View attachment "dmesg-4.3.txt" of type "text/plain" (15420 bytes)
View attachment "dmesg-4.4.txt" of type "text/plain" (15361 bytes)
View attachment "dmesg-4.4-multi.txt" of type "text/plain" (15327 bytes)
Powered by blists - more mailing lists