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Biederman) To: Sang Yan Cc: , , , , , , References: <20200814055239.47348-1-sangyan@huawei.com> Date: Fri, 14 Aug 2020 10:17:06 -0500 In-Reply-To: <20200814055239.47348-1-sangyan@huawei.com> (Sang Yan's message of "Fri, 14 Aug 2020 01:52:38 -0400") Message-ID: <87tux5i7f1.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1k6bVQ-0001vZ-PO;;;mid=<87tux5i7f1.fsf@x220.int.ebiederm.org>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/U8iQDvUHSg0k7Zv0nFYBoIQGMmYLEEDU= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on sa07.xmission.com X-Spam-Level: * X-Spam-Status: No, score=1.3 required=8.0 tests=ALL_TRUSTED,BAYES_50, DCC_CHECK_NEGATIVE,T_TM2_M_HEADER_IN_MSG,XMNoVowels autolearn=disabled version=3.4.2 X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.4795] * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa07 0; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: ; sa07 0; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: *;Sang Yan X-Spam-Relay-Country: X-Spam-Timing: total 362 ms - load_scoreonly_sql: 0.06 (0.0%), signal_user_changed: 11 (3.1%), b_tie_ro: 10 (2.7%), parse: 0.89 (0.2%), extract_message_metadata: 18 (5.0%), get_uri_detail_list: 1.18 (0.3%), tests_pri_-1000: 19 (5.1%), tests_pri_-950: 1.65 (0.5%), tests_pri_-900: 1.45 (0.4%), tests_pri_-90: 102 (28.1%), check_bayes: 100 (27.7%), b_tokenize: 4.6 (1.3%), b_tok_get_all: 4.7 (1.3%), b_comp_prob: 1.72 (0.5%), b_tok_touch_all: 85 (23.5%), b_finish: 1.12 (0.3%), tests_pri_0: 194 (53.6%), check_dkim_signature: 0.63 (0.2%), check_dkim_adsp: 2.5 (0.7%), poll_dns_idle: 0.69 (0.2%), tests_pri_10: 2.2 (0.6%), tests_pri_500: 7 (1.9%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH 1/2] kexec: Add quick kexec support for kernel X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sang Yan writes: > In normal kexec, relocating kernel may cost 5 ~ 10 seconds, to > copy all segments from vmalloced memory to kernel boot memory, > because of disabled mmu. I haven't seen kexec that slow since I tested on my 16Mhz 386. That machine has an excuse it really is slow. Anything else that takes seconds is almost certainly slow because someone has misconfigured things to not cache the data copied by kexec. I humbly suggest that you fix the arm64 code so that the data gets cached. Eric