I meant thanks Marcy (not Nancy)....wooops. K
----- Original Message ----- From: Rob van der Heij <[EMAIL PROTECTED]> Date: Thursday, October 23, 2008 11:52 am Subject: Re: Crytographic processors To: [email protected] > On Thu, Oct 23, 2008 at 4:52 PM, Marcy Cortes > <[EMAIL PROTECTED]> wrote: > > > Yes. Configured as accelerators. > > > > No figures. There isn't a velocity report on them (no > monitor data > > perhaps?). But the comments from the applications > folks was "pretty > > close" to non-SSL. > > Benchmarking it is not trivial (appears not even trivial to ensure > they are used). And there's a trade-off to be made in configuration. > > The idea is that you offload work to the crypto processor. So after > you started the work, the CPU must go back to get the results. > As it > turns out, the resolution of the Linux timer is such that it may take > longer than when you would emulate it in software. So while you save > resources on a global level, measuring a single thread doing these > encryption operations will not show you that in elapsed time. You'd > need enough parallel threads all doing encryption to show the > difference. > > To address the customer disappointed caused by this, developers added > the option to let the CPU poll (busy wait) for the crypto. For a > single thread, that means you can run the crypto operations quicker > after each other. As long as the device is faster than software > emulation, you still save CPU although not as much as without polling. > So you pay a price to reduce latency. When you have multiple threads > going for the crypto, you get a queue and operations may take longer > than when you did them yourself. With all waiting threads > spinning for > the answer, it also takes more resources then when you did it in > software. I'm not sure what the default is. > > With the breakdown of CPU usage per process in Linux, you should be > able to see the sweet spot in your benchmark when you increase the > number of threads. > > -Rob > > ----------------------------------------------------------------- > ----- > For LINUX-390 subscribe / signoff / archive access instructions, > send email to [EMAIL PROTECTED] with the message: INFO > LINUX-390 or visit > http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
