From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1YpHZd-0007wg-DW for kexec@lists.infradead.org; Mon, 04 May 2015 14:42:22 +0000 Message-ID: <5547852F.8030309@redhat.com> Date: Mon, 04 May 2015 20:11:51 +0530 From: Pratyush Anand MIME-Version: 1.0 Subject: Re: [PATCH RFC 0/3] arm64: disable/enable d-cache support for References: In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: geoff@infradead.org Cc: takahiro.akashi@linaro.org, kexec@lists.infradead.org On Monday 04 May 2015 06:32 PM, Pratyush Anand wrote: > These patches add support for enable/disable d cache support. It reduces > time for sha verification from more than 2 min to 3-4 sec on my > platform. > There are some of the observation which I am unable to explain. > * It takes around 18 sec when I boot a kexec kernel and around 3-4 sec > * when I boot a crash kernel. In case of kexec kernel start of 1st > * segment is at 0000004000280000 and, end of last segment is at > * 00000040029c0000. In case of crash kernel start of 1st segment is at > * 00000041b9080000 and, end of last segment is at 00000041f9000000. There is one more observation which is not explainable :( While executing a secondary kernel using kexec -e, if sha256_process() function is aligned at offset 256, it takes 18 sec else it takes double ie 36 sec. # objdump -d purgatory/purgatory.ro | grep sha256_process 0000000000001300 : -> takes 18 sec If because of some changes in code, this function shifts a bit # objdump -d purgatory/purgatory.ro | grep sha256_process 0000000000001310 : -> takes 36 sec. So, "__attribute__ ((aligned (256))) void sha256_process( sha256_context *ctx, const uint8_t data[64] )" guarantees constant execution time, but how can this be justified? ~Pratyush _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec