From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id 8F04F67B27 for ; Thu, 1 Jun 2006 15:26:25 +1000 (EST) Subject: Re: Collecting hypervisor call stats From: Benjamin Herrenschmidt To: Mike Kravetz In-Reply-To: <20060531225813.GC7909@w-mikek2.ibm.com> References: <20060531204144.GA7909@w-mikek2.ibm.com> <17534.7026.169023.420733@cargo.ozlabs.ibm.com> <20060531225813.GC7909@w-mikek2.ibm.com> Content-Type: text/plain Date: Thu, 01 Jun 2006 15:26:16 +1000 Message-Id: <1149139576.28307.28.camel@localhost.localdomain> Mime-Version: 1.0 Cc: linuxppc-dev@ozlabs.org, Paul Mackerras List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2006-05-31 at 15:58 -0700, Mike Kravetz wrote: > On Thu, Jun 01, 2006 at 08:40:50AM +1000, Paul Mackerras wrote: > > I think that gathering those statistics would be useful. I suggest > > you use a per-cpu array for them, to reduce the performance impact. > > Yes, that is a must do. > > We need to get a timestamp before and after the call. mftb should do > the trick. Also, I'd prefer to have the code that stuffs the values > into the array be C. So, the decision is to have the assembly code > call out to the C routine -OR- create wrappers for the assembly routines. > I much prefer C wrappers to touching the assembly. Argh... yet another use of mftb for which I'll need a cell specific workaround :( Ben.