From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751738AbdECHOp (ORCPT ); Wed, 3 May 2017 03:14:45 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:46404 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751031AbdECHOh (ORCPT ); Wed, 3 May 2017 03:14:37 -0400 Subject: Re: [PATCH v4 RFT 1/2] powerpc/fadump: reduce memory consumption for capture kernel To: Michal Suchanek , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Jonathan Corbet , Vlastimil Babka , Michal Hocko , linuxppc-dev@lists.ozlabs.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org References: <20170502155611.6789-1-msuchanek@suse.de> From: Hari Bathini Date: Wed, 3 May 2017 12:43:33 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170502155611.6789-1-msuchanek@suse.de> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable x-cbid: 17050307-0008-0000-0000-00000127A975 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17050307-0009-0000-0000-00000955CD58 Message-Id: <765ca86f-b6c5-190e-b3a9-91282e199baf@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-03_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705030140 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 02 May 2017 09:26 PM, Michal Suchanek wrote: > With fadump (dump capture) kernel booting like a regular kernel, it almost > needs the same amount of memory to boot as the production kernel, which is > unwarranted for a dump capture kernel. But with no option to disable some > of the unnecessary subsystems in fadump kernel, that much memory is wasted > on fadump, depriving the production kernel of that memory. > > Introduce kernel parameter 'fadump_append=' that would take regular kernel > parameters to be appended when fadump is active. > This 'fadump_append=' parameter can be leveraged to pass parameters like > nr_cpus=1, cgroup_disable=memory and numa=off, to disable unwarranted > resources/subsystems. > > Also, ensure the log "Firmware-assisted dump is active" is printed early > in the boot process to put the subsequent fadump messages in context. > > Suggested-by: Michael Ellerman > Signed-off-by: Hari Bathini > Signed-off-by: Michal Suchanek > --- > v4: > - use space separated arguments instead of comma separated > - do not append parameters when fadummp is disabled > --- > arch/powerpc/kernel/fadump.c | 27 ++++++++++++++++++++++++--- > 1 file changed, 24 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c > index ebf2e9c..e0c728a 100644 > --- a/arch/powerpc/kernel/fadump.c > +++ b/arch/powerpc/kernel/fadump.c > @@ -79,8 +79,10 @@ int __init early_init_dt_scan_fw_dump(unsigned long node, > * dump data waiting for us. > */ > fdm_active = of_get_flat_dt_prop(node, "ibm,kernel-dump", NULL); > - if (fdm_active) > + if (fdm_active) { > + pr_info("Firmware-assisted dump is active.\n"); > fw_dump.dump_active = 1; > + } > > /* Get the sizes required to store dump data for the firmware provided > * dump sections. > @@ -263,8 +265,12 @@ int __init fadump_reserve_mem(void) > { > unsigned long base, size, memory_boundary; > > - if (!fw_dump.fadump_enabled) > + if (!fw_dump.fadump_enabled) { > + if (fw_dump.dump_active) > + pr_warn("Firmware-assisted dump was active but kernel" > + " booted with fadump disabled!\n"); > return 0; > + } > > if (!fw_dump.fadump_supported) { > printk(KERN_INFO "Firmware-assisted dump is not supported on" > @@ -304,7 +310,6 @@ int __init fadump_reserve_mem(void) > memory_boundary = memblock_end_of_DRAM(); > > if (fw_dump.dump_active) { > - printk(KERN_INFO "Firmware-assisted dump is active.\n"); > /* > * If last boot has crashed then reserve all the memory > * above boot_memory_size so that we don't touch it until > @@ -363,6 +368,22 @@ unsigned long __init arch_reserved_kernel_pages(void) > return memblock_reserved_size() / PAGE_SIZE; > } > > +/* Look for fadump_append= cmdline option. */ > +static int __init early_fadump_append_param(char *p) > +{ > + if (!p) > + return 1; > + > + if (fw_dump.fadump_enabled && fw_dump.dump_active) { > + pr_info("enforcing additional parameters (%s) passed through " > + "'fadump_append=' parameter\n", p); > + parse_early_options(p); While testing this on a system with yaboot bootloader, it seems that parsing a parameter with syntax like fadump_append="nr_cpus numa=off" is not resulting in the intended way.. Thanks Hari