From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rune.pobox.com (rune.pobox.com [208.210.124.79]) by ozlabs.org (Postfix) with ESMTP id A7B0367B7D for ; Sat, 15 Jul 2006 18:03:27 +1000 (EST) Date: Sat, 15 Jul 2006 03:03:02 -0500 From: Nathan Lynch To: Mike Kravetz Subject: Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers Message-ID: <20060715080302.GL19076@localdomain> References: <20060714233739.GA11487@monkey.ibm.com> <20060714234034.GC11487@monkey.ibm.com> <20060715001545.GK19076@localdomain> <20060715004156.GJ6824@monkey.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20060715004156.GJ6824@monkey.ibm.com> Cc: Bryan Rosenburg , linuxppc-dev@ozlabs.org, Paul Mackerras , Arnd Bergmann , Christopher Yeoh List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Mike Kravetz wrote: > On Fri, Jul 14, 2006 at 07:15:45PM -0500, Nathan Lynch wrote: > > Hmm, isn't it possible that the stats could be corrupted if we process > > an interrupt/softirq which does an hcall while the stats are being > > updated? Maybe it's not a show-stopper, but it seems to me that > > accuracy could suffer under some workloads. > > Yes, they can become inaccurate. Is this what you mean by 'corrupted' or > you thinking of something worse? Yes, "corrupted" was perhaps too strong, but we could lose the accounting for hcalls from interrupts that we take at exactly the wrong time. I guess it's a pretty tiny risk. I just wanted to make sure this had been considered, but if you're comfortable with the overhead/accuracy tradeoff, then okay.