From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: Re: [Cbe-oss-dev] [RFC, PATCH 4/4] Add support to OProfile for profiling Cell BE SPUs -- update From: Benjamin Herrenschmidt To: maynardj@us.ibm.com In-Reply-To: <45BFCC8E.4000008@us.ibm.com> References: <45BE4ED0.5030808@us.ibm.com> <45BE4FA4.9020105@us.ibm.com> <200701300839.05144.arnd@arndb.de> <45BFBB78.7060907@us.ibm.com> <45BFCC8E.4000008@us.ibm.com> Content-Type: text/plain Date: Wed, 31 Jan 2007 10:34:03 +1100 Message-Id: <1170200044.26655.349.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Arnd Bergmann , cbe-oss-dev@ozlabs.org, oprofile-list@lists.sourceforge.net, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > I've given this some more thought, and I'm coming to the conclusion that > a pure array-based implementation for holding cached_info (getting rid > of the lists) would work well for the vast majority of cases in which > OProfile will be used. Yes, it is true that the mapping of an SPU > context to a phsyical spu-numbered array location cannot be guaranteed > to stay valid, and that's why I discard the cached_info at that array > location when the SPU task is switched out. Yes, it would be terribly > inefficient if the same SPU task gets switched back in later and we > would have to recreate the cached_info. However, I contend that > OProfile users are interested in profiling one application at a time. > They are not going to want to muddy the waters with multiple SPU apps > running at the same time. I can't think of any reason why someone would > conscisouly choose to do that. > > Any thoughts from the general community, especially OProfile users? Well, it's my understanding that quite a few typical usage scenario involve different tasks running on different SPUs passing each other data around. Ben.