Can't you do something with outside profiling tools? For instance oprofile?
http://oprofile.sourceforge.net/
That's a (linux) kernel-level profiler that can gather fairly useful
bits of information without having to run a modified version of
memcached and without having to run it permanently.
Have a look at the examples, especially the "Symbol summary for a single
application including libraries". It appears to be a sampling profiler,
so it might not give you exactly what you want.
There is also the 'new' perf-module for linux kernels:
https://perf.wiki.kernel.org/
But that seems to gather similar statistics at its most detailed level.
Other than that, you could look at tools at the network-layer-level.
Even outside the server by using the port mirroring feature from a
decent managed switch.
Best regards,
Arjen
On 13-7-2013 0:58 Manish Jain wrote:
Nice. Is there any methodology I could apply to actually gather server
side response times, say even at the cost of slightly performance
degradation?
On Fri, Jul 12, 2013 at 3:47 PM, dormando <[email protected]
<mailto:[email protected]>> wrote:
On a healthy machine, over the network, and memcached isn't overloaded,
0.1ms response times are what you should expect.
On Fri, 12 Jul 2013, Manish Jain wrote:
> Then, what would be a reasonable estimate of latency of GET and
SET operations on memcached server? A milli second?
> -mrjn
>
>
>
> On Fri, Jul 12, 2013 at 3:32 PM, dormando <[email protected]
<mailto:[email protected]>> wrote:
> Those don't really lag... just "stats sizes", so don't call
that one. Also
> "stats cachedump" isn't very fast.
>
> If there's any latency at all on a standard operation it's
almost always
> an outside issue (swap, network, etc), or a massive fault
of the software.
>
> Just adding timing measurements internally slows down the
entire operation
> significantly, which is why we don't do it.
>
> On Fri, 12 Jul 2013, Manish Jain wrote:
>
> > Is there a way to get server side latency stats for
Memcached operations, like GET, SET, INCREMENT etc?
> > memcached stats tells you total number of gets and sets,
but doesn't indicate anything about the latency of those operations.
> >
> > Cheers,
> > Manish
> >
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