From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx125.postini.com [74.125.245.125]) by kanga.kvack.org (Postfix) with SMTP id 22F526B0089 for ; Sun, 14 Jul 2013 21:38:52 -0400 (EDT) Received: by mail-ie0-f170.google.com with SMTP id e11so25031448iej.15 for ; Sun, 14 Jul 2013 18:38:51 -0700 (PDT) Message-ID: <51E3529F.6070909@gmail.com> Date: Mon, 15 Jul 2013 09:38:39 +0800 From: Sam Ben MIME-Version: 1.0 Subject: Re: boot tracing References: <1373594635-131067-1-git-send-email-holt@sgi.com> <20130712082756.GA4328@gmail.com> <20130712084712.GD24008@pd.tnic> <20130712085341.GC4328@gmail.com> In-Reply-To: <20130712085341.GC4328@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Ingo Molnar Cc: Borislav Petkov , Robin Holt , Robert Richter , "H. Peter Anvin" , Nate Zimmer , Linux Kernel , Linux MM , Rob Landley , Mike Travis , Daniel J Blueman , Andrew Morton , Greg KH , Yinghai Lu , Mel Gorman , Peter Zijlstra On 07/12/2013 04:53 PM, Ingo Molnar wrote: > * Borislav Petkov wrote: > >> On Fri, Jul 12, 2013 at 10:27:56AM +0200, Ingo Molnar wrote: >>> Robert Richter and Boris Petkov are working on 'persistent events' >>> support for perf, which will eventually allow boot time profiling - >>> I'm not sure if the patches and the tooling support is ready enough >>> yet for your purposes. >> Nope, not yet but we're getting there. >> >>> Robert, Boris, the following workflow would be pretty intuitive: >>> >>> - kernel developer sets boot flag: perf=boot,freq=1khz,size=16MB >> What does perf=boot mean? I assume boot tracing. > In this case it would mean boot profiling - i.e. a cycles hardware-PMU > event collecting into a perf trace buffer as usual. > > Essentially a 'perf record -a' work-alike, just one that gets activated as > early as practical, and which would allow the profiling of memory > initialization. > > Now, one extra complication here is that to be able to profile buddy > allocator this persistent event would have to work before the buddy > allocator is active :-/ So this sort of profiling would have to use > memblock_alloc(). Could perf=boot be used to sample the performance of memblock subsystem? I think the perf subsystem is too late to be initialized and monitor this. > > Just wanted to highlight this usecase, we might eventually want to support > it. > > [ Note that this is different from boot tracing of one or more trace > events - but it's a conceptually pretty close cousin. ] > > Thanks, > > Ingo > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org