Subject: Re: AMD Geode LX Security Block (was Re: NetBSD on the Soekris net5501 status report)
To: Ben Harris <email@example.com>
From: Jason Thorpe <firstname.lastname@example.org>
Date: 06/18/2007 16:14:54
On Jun 18, 2007, at 3:32 PM, Ben Harris wrote:
> In article <9BCD26A4-4861-46EE-8FF8-A5DEDDCA0405@invisible.ca> you
>> On 18-Jun-07, at 8:16 AM, Pawel Jakub Dawidek wrote:
>>> I'd suggest correctness verification. ~15GB/s seems to be waaaay
>>> too fast:)
>> You're right, the results vary greatly from run to run. I've seen
>> numbers considerably lower than this as well as numbers considerably
>> higher. Not exactly sure why, maybe openssl has the timing wrong --
>> it claims that it's running for 3s on n size blocks, but then later
>> claims that it only ran for a fraction of that period of time, ie:
> I haven't checked the code, but my guess would be that 'openssl speed'
> runs for 3s of real time, but then checks the amount of CPU time it's
> used. Since the CPU is idle waiting for the result from the
> accelerator, the CPU time is roughly zero, hence the ludicrous
That said, my examination of the code revealed a busy-wait in the
glxsb driver waiting for the AES operation to complete, which includes
a bus_space_read_4() in the tight (without delay) loop.
Seems like that ought to use a callout instead.