Re: Linux Kernel Markers - performance characterization with large IO load on large-ish system

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Ingo Molnar wrote:
actually, the pure marker overhead seems to be a regression:

Kernel Options       Min val    Avg val    Max val    Std Dev
- markers - bt cfg  15.349127  16.169459  16.372980   0.184417
+ markers - bt cfg  15.280382  16.202398  16.409257   0.191861

why isnt the marker near zero-cost as it should be? (as long as they are enabled but are not in actual use) 2% increase is _ALOT_.

The increase in the mean is actually 0.033, or 0.2%.

So there's something wrong going on - either markers have unacceptably high cost, or the measurement is not valid.

The third option is that the measurement just needs to be done more times. The standard error in the mean for the + markers case is 0.191861 / sqrt(10) = 0.061, which is twice the size of the difference being measured.
Joshua Root,  jmr AT
To unsubscribe from this list: send the line "unsubscribe linux-btrace" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at

[Netdev]     [Linux Wireless]     [Kernel Newbies]     [Memory]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Photo]     [Yosemite]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]     [Video 4 Linux]     [Linux Resources]

Add to Google