On Wed, Dec 02, 2015 at 04:36:50PM -0800, Greg KH wrote:
On Wed, Dec 02, 2015 at 05:50:30PM -0600, Victor Rodriguez wrote:
On Tue, Dec 1, 2015 at 7:32 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
On Tue, Dec 01, 2015 at 06:45:51PM -0600, Victor Rodriguez wrote:
Hi
Despite the fact that this is not a well formulated question. I wonder what tests could be a good subset to measure the performance of the kernel . I have some approaches like phoronix does here :
http://www.phoronix.com/scan.php?page=article&item=linux-41-byt&num=1
I am sure postmark/ John the ripper/ Apache are good candidates but I want to ask the community if there is some specific test that you recommend
It depends on what you want to test, specifically. The "kernel" isn't a very specific thing, what most of those tests test is the speed of the hardware, not specifically the kernel itself.
good luck,
greg k-h
Thanks for the feedback . You are right they test the speed of the HW however I have seen that when there is a change in the kernel for network the performance of apache is changed, which make total sense .
Maybe, maybe not, depending on if "apache" is cpu or hardware bound (networking hardware has physical limits...) again, you have to be very sure about exactly what you are wanting to test before using such a test to try to "validate" anything other than just raw hardware speed.
Take a look at the "old" lmbench set of benchmarks for valid things that a kernel change can affect, it's much different from what you might be thinking of as a test.
We also still use lmbench as the usual first level of assessment as it gives a lot of information about the change set impact on low-level functions (system-calls, IPC, allocation...) was. It is much more precise than trying to detect changes in complex applications that might only be making a handful of a affected system call and thus look like performance did not change while it actually did - just its in some hard to reach corner case. As with all testing - you need layers of testing to get a usable picture of what is going on and lmbench is a good candidate for the lowest level. Deducing system level changes from looking at complex application performance changes is alost impossible. Specifically lmbench has a simple make results; make rerun which can give a good overview of differences - but actually the tests default runs are only a small part of what the tests can uncover so looking at individual microbenchmarks to discover latency/bandwidth changes can be very helpful also to uncover odd hardware behavior. Some other low-level benchmarks we use are: rt-tests - scheduling, pi NetPIPE - network bandwidth bonnie++ - filesystem thx! hofrat