Opened 15 years ago

Closed 11 years ago

#567 closed enhancement (fixed)

v.kernel: suspected i/o bottleneck

Reported by: dylan Owned by: grass-dev@…
Priority: normal Milestone: 6.5.0
Component: Default Version: svn-develbranch6
Keywords: v.kernel Cc:
CPU: x86-32 Platform: Linux


v.kernel seems to have a disk i/o bottleneck, that starts to cause problems with moderately large input vector files. I use this command with <3000 point features, with a small region setting: approx 500x500 cells, regularly without issue. Trying out a larger dataset, 22k point features -- same region geometry, results in a lot of disk activity and very slow run-times. I took a peak at the source code, and it looks like there are several calls to a spatial index. There was some chatter on the mailing list a while back regarding improvement in the way that the spatial index is created. I wonder if this would improve v.kernel when working with a large number of features.

The reason that I suspect some kind of I/O issue -- I hear a lot of disk trashing while this module is running. Also note that it is using very little memory... perhaps some caching would speed things up.

Some details on the environment:

# region info:
rows:       632
cols:       364
cells:      230048

# command and arguments
# file 'soilweb_queries' has approx 22k records
v.kernel --o in=soilweb_queries out=swq std=50000

Change History (3)

comment:1 by hamish, 15 years ago

can you run it with "time"? ie:

time v.kernel --o in=soilweb_queries out=swq std=50000

that will say how much time is spent doing the work, and how much time is taken up by the kernel dealing i/o stuff, etc.


comment:2 by dylan, 15 years ago

Some data:


Hmm... the sys times do not seem to dominate, rather they approach that of the usr time.

comment:3 by neteler, 11 years ago

Resolution: fixed
Status: newclosed

v.kernel has been made faster in r54108, r53983, r53982, r53956, r53896. See also trac #1800. Closing this report as fixed.

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