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From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
To: Petr Mladek <pmladek@suse.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>,
	ruifeng.zhang1@unisoc.com,
	Steven Sistare <steven.sistare@oracle.com>,
	Prarit Bhargava <prarit@redhat.com>, Baoquan He <bhe@redhat.com>,
	zhang.lyra@gmail.com, cixi.geng1@unisoc.com,
	Orson Zhai <orsonzhai@gmail.com>, Dave Young <dyoung@redhat.com>,
	Vivek Goyal <vgoyal@redhat.com>,
	Pavel Tatashin <pasha.tatashin@soleen.com>,
	John Ogness <john.ogness@linutronix.de>,
	Steven Rostedt <rostedt@goodmis.org>,
	Jon DeVree <nuxi@vault24.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Salvatore Bonaccorso <carnil@debian.org>,
	Stephen Boyd <sboyd@kernel.org>,
	kexec@lists.infradead.org, linux-kernel@vger.kernel.org,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Orson Zhai <orson.zhai@unisoc.com>,
	John Stultz <john.stultz@linaro.org>
Subject: Re: [RFC PATCH] printk: Change timestamp to triplet as mono, boot and real
Date: Thu, 13 Aug 2020 20:31:55 +0900	[thread overview]
Message-ID: <20200813113155.GA483@jagdpanzerIV.localdomain> (raw)
In-Reply-To: <20200813102258.GL12903@alley>

On (20/08/13 12:22), Petr Mladek wrote:
>
>   + would take more space (prefix + text vs. binary representation)

Dict buffer is allocated regardless of how we use it, and only printks
from drivers/* (dev_printk*) add dict payload. It might be the case
that on some (if not most) systems dict pages are not used 90% of times
(if not 99%).

>   + not reliable because dict is currently dropped when no space

Well, in the perfect world this is a problem, but "maybe not having
alternative timestamps sometimes" can be OK approach for people who
wants to use those triplet timestamps.

But, in general, how real this problem is? What I sae so far (on my boxes)
was that printk messages are longer than dict payload.

Example:

6,223,93298,-,caller=T1;acpi PNP0A08:00: _OSC: OS supports [Segments MSI HPX-Type3]
 SUBSYSTEM=acpi
 DEVICE=+acpi:PNP0A08:00
6,224,93413,-,caller=T1;acpi PNP0A08:00: _OSC: not requesting OS control; OS requires [ExtendedConfig ASPM ClockPM MSI]
 SUBSYSTEM=acpi
 DEVICE=+acpi:PNP0A08:00
6,225,93540,-,caller=T1;PCI host bridge to bus 0000:00
6,226,93541,-,caller=T1;pci_bus 0000:00: root bus resource [io  0x0000-0x0cf7 window]
 SUBSYSTEM=pci_bus
 DEVICE=+pci_bus:0000:00

It might be the case, that overflowing dict buffer, without first overflowing
printk buffer, can be rather challenging.

>   + it would make the controversial dictionary feature more important

Yes. But, for the time being, this controversial dict feature allocates
pages for dict buffer anyway.

	-ss

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  reply	other threads:[~2020-08-13 11:32 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-11  4:40 [RFC PATCH] printk: Change timestamp to triplet as mono, boot and real Orson Zhai
2020-08-11  4:56 ` Randy Dunlap
2020-08-11  9:44 ` Petr Mladek
2020-08-11 12:05   ` Thomas Gleixner
2020-08-11 13:02     ` Petr Mladek
2020-08-11 13:43       ` Prarit Bhargava
2020-08-13  1:55       ` Sergey Senozhatsky
2020-08-13 10:22         ` Petr Mladek
2020-08-13 11:31           ` Sergey Senozhatsky [this message]
2020-08-14  9:50             ` Petr Mladek
2020-08-13 10:26         ` Thomas Gleixner
2020-08-14  6:34 ` Dave Young

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