From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: Kernel Start-up Time
Date: Tue, 19 Jan 2010 09:02:35 +0000 [thread overview]
Message-ID: <20100119090235.GC24447@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <201001191036.21594.caglarakyuz@gmail.com>
On Tue, Jan 19, 2010 at 10:36:21AM +0200, Caglar Akyuz wrote:
> What I'm looking for is whether early arm boot sequence is 1.3 secs or not. I
> may be wrong but my guess is before jumping to generic "start_kernel" function
> following files are executed:
>
> * arch/arm/kernel/head.S
> * arch/arm/kernel/head-common.S
> * arch/arm/mm/proc-arm926.S
>
> And these 3 files cost me 1.3 seconds. Initializing page tables, caches etc
> costing that much doesn't seem optimal to me. This is what I'm trying to find
> out.
Only if your CPU is really inefficient when caches are turned off will
it take 1.3 seconds.
Try reading a cycle counter at the start of head.S, save it in memory.
Read it again in start_kernel() and save it somewhere again, and
compare the two values. I think you'll find that it's not this code
which is taking 1.3 seconds.
next prev parent reply other threads:[~2010-01-19 9:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-18 8:10 Kernel Start-up Time Caglar Akyuz
2010-01-18 8:39 ` Tonyliu
2010-01-18 8:54 ` Caglar Akyuz
2010-01-18 15:39 ` Steve Chen
2010-01-18 19:39 ` Dirk Behme
2010-01-19 8:40 ` Caglar Akyuz
2010-01-19 8:36 ` Caglar Akyuz
2010-01-19 9:02 ` Russell King - ARM Linux [this message]
2010-01-19 14:31 ` Caglar Akyuz
2010-01-19 11:04 ` Bahadir Balban
2010-01-19 14:40 ` Caglar Akyuz
2010-01-19 11:04 ` Johannes Stezenbach
2010-01-19 14:35 ` Caglar Akyuz
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20100119090235.GC24447@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).