[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference turris::digital_unix

Title:	DIGITAL UNIX(FORMERLY KNOWN AS DEC OSF/1)
Notice:	Welcome to the Digital UNIX Conference
Moderator:	SMURF::DENHAM

Created:	Thu Mar 16 1995
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	10068
Total number of notes:	35879

8687.0. "potential memory alignment issue" by SCASS1::GROVE () Mon Feb 03 1997 16:59

    
    
    A customer of mine is running a third-party application called Muscato
    on an AlphaServer 4100 with the Digital UNIX version 4.0A.  The Muscato
    application has recently been ported to the Digital UNIX Alpha
    platform.  The customer is seeing poor performance and feels there may
    be a memory alignment error.  Is there a tool to look for memory
    alignment issues or provide the number of alignment faults on a process
    basis?
    
    I searched the atom man page for 'alignment', to no avail.  Is there
    any potential that this tool could assist?
    
    Thanks

T.R	Title	User	Personal Name	Date	Lines
8687.1	See man uac	DECC::SULLIVAN	Jeff Sullivan	`Mon Feb 03 1997 17:16`	17
	If Unaligned Access Messages are turned off (which they may be by default while using CDE), you should turn them back on. % uac p parent printing is on fixup is on sigbus is off You can also have use uac to deliver a SIGBUS signal to the parent process, which you could debug using dbx/ladebug. See also http://fluid.mro.dec.com/www-swdev/pages/Home/TECH/faqs/dunix/unalign.html and a few related topics in this notes conference. -Jeff
8687.2	CDE turns them off?	VAXCPU::michaud	Jeff Michaud - ObjectBroker	`Mon Feb 03 1997 19:00`	4
	> If Unaligned Access Messages are turned off (which they may be by default while > using CDE), you should turn them back on. Out of curiosity, why does CDE turn them off?
8687.3		DECCXL::MARIO		`Mon Feb 03 1997 19:25`	8
	re: .2 > Out of curiosity, why does CDE turn them off? The default reporting of unaligned access messages was accidently turned off by default in CDE in the UNIX V4.0 release. I understand it was fixed as of V4.0a and unaligned access are reported now by default.
8687.4	See OSF_QAR 45656	DECC::SULLIVAN	Jeff Sullivan	`Tue Feb 04 1997 12:57`	28
	And the answer (from Chris Beute) is... ======================================================================= This fix was not accepted into the re-opened Platinum kit, but it has been submitted for Steel BL1. Chris 4/25/96 ======================================================================= Problem is fixed in Steel, and patches are available for V4.x 12/2/96 I added this to my ~/.cshrc to workaround the problem: # Workaround for OSF_QAR 45656 (CDE disables uac) uac p 1 In the compiler group, we absolutely need to know when unaligned accesses occur. We were none too pleased to come across this unintended "feature". As stated above, the problem has since been addressed, but I'd double-check on the system in question, just to be sure. -Jeff