Re: posix_fadvise()

[Rick Jones <rick.jones2 () hpe com>]

On 04/19/2016 10:02 AM, Denis Ovsienko wrote:
> Hello list.
>
> As far as documentation goes, some sense may be presumed in libpcap
> calling posix_fadvise() with POSIX_FADV_SEQUENTIAL. This way the OS
> would be able to adjust the buffers better to read the .pcap file.
> Does anybody have any practical experience with posix_fadvise() to
> comment if the gain is ever visible with present day hardware and
> OSes?

Well, in the long ago and far away when web server benchmarking was all 
the rage, I and others with whom I was working found that getting a web 
server to use posix_fadvise() to tell the file system the web server was 
no longer interested in trailing sections of its access log was a clear 
win for keeping less-frequently but still accessed URLs in the file cache.

If nothing else, if tcpdump isn't doing so already it would be a 
worthwhile thing to add to the writing of the capture file.  And, for 
that matter, just about anything generating logfiles...

happy benchmarking,

rick jones

[Note to moderator:  I've updated my subscription to my new email and 
cancelled the post that got moderated.]
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