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From: David Hildenbrand <david@redhat.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Baoquan He <bhe@redhat.com>, Donald Dutile <ddutile@redhat.com>,
	Jiri Bohac <jbohac@suse.cz>, Vivek Goyal <vgoyal@redhat.com>,
	Dave Young <dyoung@redhat.com>,
	kexec@lists.infradead.org, Philipp Rudo <prudo@redhat.com>,
	Pingfan Liu <piliu@redhat.com>, Tao Liu <ltao@redhat.com>,
	linux-kernel@vger.kernel.org,
	David Hildenbrand <dhildenb@redhat.com>
Subject: Re: [PATCH v2 0/5] kdump: crashkernel reservation from CMA
Date: Fri, 30 May 2025 11:11:40 +0200	[thread overview]
Message-ID: <04a49de5-eb79-431b-ba5b-eae2536781c6@redhat.com> (raw)
In-Reply-To: <aDl1ViMpK_6q_z06@tiehlicka>

On 30.05.25 11:07, Michal Hocko wrote:
> On Fri 30-05-25 10:39:39, David Hildenbrand wrote:
>> On 30.05.25 10:28, Michal Hocko wrote:
> [...]
>>> All that being said I would go with an additional parameter to the
>>> kdump cma setup - e.g. cma_sane_dma that would skip waiting and use 10s
>>> otherwise. That would make the optimized behavior opt in, we do not need
>>> to support all sorts of timeouts and also learn if this is not
>>> sufficient.
>>>
>>> Makes sense?
>>
>> Just so I understand correctly, you mean extending the "crashkernel=" option
>> with a boolean parameter? If set, e.g., wait 1s, otherwise magic number 10?
> 
> crashkernel=1G,cma,cma_sane_dma # no wait on transition

But is no wait ok? I mean, any O_DIRECT with any device would at least 
take a bit, no?

Of course, there is a short time between the crash and actually 
triggerying kdump.

> crashkernel=1G,cma # wait on transition with e.g. 10s timeout

In general, would work for me.

-- 
Cheers,

David / dhildenb



  reply	other threads:[~2025-05-30  9:17 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-20 16:48 [PATCH v2 0/5] kdump: crashkernel reservation from CMA Jiri Bohac
2025-02-20 16:51 ` [PATCH v2 1/5] Add a new optional ",cma" suffix to the crashkernel= command line option Jiri Bohac
2025-03-03  1:51   ` Baoquan He
2025-02-20 16:52 ` [PATCH v2 2/5] kdump: implement reserve_crashkernel_cma Jiri Bohac
2025-02-20 16:54 ` [PATCH v2 3/5] kdump, documentation: describe craskernel CMA reservation Jiri Bohac
2025-03-03  1:54   ` Baoquan He
2025-02-20 16:55 ` [PATCH v2 4/5] kdump: wait for DMA to finish when using CMA Jiri Bohac
2025-03-03  2:02   ` Baoquan He
2025-03-11 12:00     ` Jiri Bohac
2025-02-20 16:57 ` [PATCH v2 5/5] x86: implement crashkernel cma reservation Jiri Bohac
2025-03-03  2:08 ` [PATCH v2 0/5] kdump: crashkernel reservation from CMA Baoquan He
2025-03-03  8:25 ` David Hildenbrand
2025-03-03 14:17   ` Donald Dutile
2025-03-04  4:20     ` Baoquan He
2025-05-28 21:01       ` David Hildenbrand
2025-05-29  7:46         ` Michal Hocko
2025-05-29  9:19           ` Michal Hocko
2025-05-30  8:06           ` David Hildenbrand
2025-05-30  8:28             ` Michal Hocko
2025-05-30  8:39               ` David Hildenbrand
2025-05-30  9:07                 ` Michal Hocko
2025-05-30  9:11                   ` David Hildenbrand [this message]
2025-05-30  9:26                     ` Michal Hocko
2025-05-30  9:28                       ` David Hildenbrand
2025-05-30  9:34                     ` Jiri Bohac
2025-05-30  9:47                       ` David Hildenbrand
2025-05-30  9:54                         ` Michal Hocko
2025-05-30 10:06                         ` Jiri Bohac
2025-05-29 16:22         ` Jiri Bohac
2025-03-12 15:36   ` Jiri Bohac

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