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LWN.net Weekly Edition for May 23, 2013
An "enum" for Python 3
An unexpected perf feature
LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
I don't like using bits in pointers to carry extra information. That kind of thing comes back to bite you sooner or later.
Posted Mar 29, 2007 19:49 UTC (Thu) by GreyWizard (guest, #1026)
Posted Mar 30, 2007 21:10 UTC (Fri) by venkip (subscriber, #37888)
The current timer infrastructure and the changes done is for per CPU timers. That is each CPU looks at all the timers scheduled on it independently. So, such a pointer has to be atleast per CPU. Cost of such a pointer is that we will have to go through timer wheel to find next non-deferrable timer and more importantly, we have to have different set of interfaces for these deferrable and non-deferrable or have extra space in timer structure to indicate the nature of timer so that this pointer can be updated correctly when one non-deferrable tiemr expires.
Mask bits in pointers
Posted Mar 30, 2007 21:13 UTC (Fri) by venkip (subscriber, #37888)
Thing to note is that the pointers being reused are pointer to a per CPU structure that doesnt change over time. This structure is allocated at boot time and stays same. So, risk of coming back to biting me is slightly smaller :-)
Posted Mar 30, 2007 21:19 UTC (Fri) by proski (subscriber, #104)
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