[Info-vax] SAMBA really sloooow on OVMS Integrity. Any Ideas????

[IanMiller]

On Aug 18, 3:22 pm, Jan-Erik Soderholm <jan-erik.soderh... at telia.com>
wrote:
> On 2010-08-18 17:11, Bob Koehler wrote:
>
> >     ...the instruction that accesses the data will
> >     cause an alignment fault, which will get trapped, the data fetch
> >     will be fixed up, and then the fault dismissed.  This takes longer
> >     than just fixing up the access in the first place.
>
> And the main point here is that it takes *MUCH* longer on
> Itanium then on Alpha. Alpha "fixed" it in the PAL code,
> Itanium interrupts all way back the VMS kernel to get it fixed.
>
> Each alignment fault on IA64 is 10-100 times more costly
> (time-wise) then on Alpha.
>
> >     There are tools in VMS to monitor alignment faults, but I've never
> >     used them so someone else will have to chime in here.
>
> And only available on IA64, as far as I know.
>
>


Note FLT$SDA - Alignment Fault Tracing Utility is available on OpenVMS
Alpha V8.2 and later and is documented at
http://h71000.www7.hp.com/doc/82final/6549/6549pro_030.html#sda_flt

There is a performance penalty for alignment faults on Alpha but it is
not as noticeable as on I64.