From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 80E8C1A06DF for ; Thu, 11 Jun 2015 12:23:39 +1000 (AEST) Received: from mail-pd0-x22e.google.com (mail-pd0-x22e.google.com [IPv6:2607:f8b0:400e:c02::22e]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id DD5DF1402B2 for ; Thu, 11 Jun 2015 12:23:38 +1000 (AEST) Received: by pdjn11 with SMTP id n11so48633591pdj.0 for ; Wed, 10 Jun 2015 19:23:36 -0700 (PDT) Message-ID: <1433989359.31423.28.camel@axtens.net> Subject: Re: [PATCH V8 01/10] powerpc, perf: Drop the branch sample when 'from' cannot be fetched From: Daniel Axtens To: Anshuman Khandual Cc: linuxppc-dev@ozlabs.org, mikey@neuling.org, sukadev@linux.vnet.ibm.com Date: Thu, 11 Jun 2015 12:22:39 +1000 In-Reply-To: <5578274A.8080402@linux.vnet.ibm.com> References: <1433763511-5270-1-git-send-email-khandual@linux.vnet.ibm.com> <1433906475.3096.1.camel@axtens.net> <5578274A.8080402@linux.vnet.ibm.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-XrSLTfcSSd6AIHVaW/CY" Mime-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-XrSLTfcSSd6AIHVaW/CY Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi, On Wed, 2015-06-10 at 17:32 +0530, Anshuman Khandual wrote: > On 06/10/2015 08:51 AM, Daniel Axtens wrote: > > Hi Anshuman, > >=20 > > Was there a cover letter for this series that I missed? >=20 > This is the continuation (rebased and reworked) of the series > posted at https://lkml.org/lkml/2014/5/5/153 (which is V6). I > remember to have incremented the count for the re-send of the > first four patches of the series to Peter Z for generic review > which got pulled in last year. These patches here are the > remaining powerpc part of the original series. Will list down > the current changes as well next time around along with the new > ones. >=20 > >=20 > > On Mon, 2015-06-08 at 17:08 +0530, Anshuman Khandual wrote: > >> BHRB is a rolling buffer. Hence we might end up in a situation where > > Could you spell out what BHRB stands for? >=20 > Branch History Rolling Buffer, would you like to have that in the > commit message as well ? Yes please. >=20 > >=20 > >> we have read one target address but when we try to read the next entry > >> indicating the from address of the targe, the buffer just overflows. > > target? >=20 > Yeah its target address. Ok, I was just trying to point out the spelling mistake above. >=20 > >=20 > >> In this case, the captured from address will be zero which indicates > >> the end of the buffer. > >> > > In what sort of situations would this occur? It seems like something we > > would want to avoid if possible? >=20 > Its not avoidable. During regular flow of branch recording, the HW would > have written both the records correctly but then the new ones came in and > we just happen to loose one of them causing this situation. OK. Regards, Daniel --=-XrSLTfcSSd6AIHVaW/CY Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: GPGTools - https://gpgtools.org iQIcBAABCAAGBQJVePDvAAoJEPC3R3P2I92Fn6AP/1WUsoQmFO5dGZSw1sF9mcm8 fyXpgVSpT6qzFeixs5Des4XQdHbB7BWhLJxgXexL7Cgixt1GRnsWcyIkoXhaE2pN E+BycJEtmVkqsEbTuD2vUXQIcuXqymYfeufMLiFloCDracpdpqoiEO139KIhAKKh WpQCA9uTKOCNvgwhV2aAtKsma8z36YOKIQYK/zCAhppxWQ9mWsBf3MWQglpASQh7 YAlkhLPWBZk4VdtD9so8C/SpkWII63fkKVEIzW59w1eJ2OJu/hj8B7DOgjxFzdS9 FhmIgKs2w3OZaAaCe3S9RHorsRzZZzkqD1h4XAaFi53fZcoTv5UG65AeqMIA+X/8 9s2acmrDHuboLUqdXh6FyLzEFlXqkrBGkU766DQok8UoUdjm90YhtSkFu5HKfLc0 qwtVEyEvq2k7j8DlHT85pjE/fMxKw33Gcbl+ipy9zwxskelnpqUzAELGzaKSQyHO wS3+jfGMgp8CWkh7oYeKaQPmJggAuabbx3PE537tJ2CK4uh5FkC7FnZ7mrzT3YuS H+qTPjhe6KNdbh4yHOtAUVfV05m1zkWlmu5YYsSqZepI7E9QN5AjtouCpD3eudQ5 AzpwNiIhoxnbXmQPGsR1FQdOaLKPMH5b1sLkNgXE8AdAPoRwcQyAhN2PJxiIAvVB bs0RkqSXsNrzsVTXnYvY =iSMK -----END PGP SIGNATURE----- --=-XrSLTfcSSd6AIHVaW/CY--