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Re: select/poll bug?
On Sat, Aug 02, 2008 at 11:25:17AM -0400, Christos Zoulas wrote:
> The select family of system calls is generally inferior to poll because:
> 1. Expensive because you need do operations on bitmasks [ffs/shifts].
> 2. Expensive because you need to reset the masks before each call.
> 3. Non portable behavior for >= 256 fd's. All systems need source
> recompilation; some older systems need kernel recompilation.
> 4. Non-portable behavior with respect to ERESTART.
> 5. Non-portable behavior when running out of resources. The only
> way to fix this is using non-blocking-io which is a bit of a pain.
> 6. Non-portable behavior with respect to "struct timeval *timeout".
> This is non-const, and it was originally intended to return
> the time left. Most implementations did not change "timeout", but
> one or two did, so it is always good to re-initialize "timeout".
> 7. Can only report 3 types of events, read/write/except.
OTOH, poll on Mac OS X does NOT work properly on device file
descriptors, which means that any code that wants to work on Mac OS X
usually has checks in configure scripts for Darwin, and
wrappers/transform functions around poll, reimplementing it in terms
of select for that one platform.
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