Public bug reported:
ubuntuone-syncdaemon is polling at 10Hz on a read on file descriptor 4
(which appears to be a pipe). Polling waits at 10Hz is quite
excessive, especially on an idle system. For example, on a cleanly
installed Lenovo X220i, this constitutes ~7-8% of the total wakeups on
an idle system. Polling loops consume power and reduce laptop battery
life.
The 10Hz poll on a read can be observed using:
strace -f /usr/lib/ubuntuone-client/ubuntuone-syncdaemon
[pid 11786] read(14, 0x294d1a4, 4096) = -1 EAGAIN (Resource temporarily
unavailable)
[pid 11786] poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}, {fd=14,
events=POLLIN}, {fd=43, events=POLLIN}, {fd=44, events=POLLIN}, {fd=8,
events=POLLIN}, {fd=42, events=POLLIN}, {fd=3, events=POLLIN}, {fd=49,
events=POLLIN}], 9, 101) = 0 (Timeout)
[pid 11786] read(14, 0x294d1a4, 4096) = -1 EAGAIN (Resource temporarily
unavailable)
[pid 11786] poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}, {fd=14,
events=POLLIN}, {fd=43, events=POLLIN}, {fd=44, events=POLLIN}, {fd=8,
events=POLLIN}, {fd=42, events=POLLIN}, {fd=3, events=POLLIN}, {fd=49,
events=POLLIN}], 9, 101) = 0 (Timeout)
[pid 11786] read(14, 0x294d1a4, 4096) = -1 EAGAIN (Resource temporarily
unavailable)
[pid 11786] poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}, {fd=14,
events=POLLIN}, {fd=43, events=POLLIN}, {fd=44, events=POLLIN}, {fd=8,
events=POLLIN}, {fd=42, events=POLLIN}, {fd=3, events=POLLIN}, {fd=49,
events=POLLIN}], 9, 101) = 0 (Timeout)
I would expect that the correct policy here is to do a blocking read but
for some reason this is not happening hence the need for a poll. Either
the read mechanism should be re-engineered to get rid of the polling or
the polling interval should be increased to something a little more
friendly on the battery life (e.g. once every second or two).
ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: ubuntuone-client 2.0.0-0ubuntu2.2
ProcVersionSignature: Ubuntu 3.0.0-14.23-generic 3.0.9
Uname: Linux 3.0.0-14-generic x86_64
ApportVersion: 1.23-0ubuntu4
Architecture: amd64
Date: Tue Dec 20 14:51:53 2011
EcryptfsInUse: Yes
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
PackageArchitecture: all
SourcePackage: ubuntuone-client
UbuntuOneSyncdaemonExceptionsLog:
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: ubuntuone-client (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug oneiric running-unity
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https://bugs.launchpad.net/bugs/906924
Title:
ubuntuone-syncdaemon is polling at 10Hz on a pipe read
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