From: "Gleb O. Raiko" <raiko@niisi.msk.ru>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: Al Cooper <alcooperx@gmail.com>,
linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] MIPS: Kernel hangs occasionally during boot.
Date: Wed, 09 Nov 2011 15:26:32 +0400 [thread overview]
Message-ID: <4EBA6368.6030503@niisi.msk.ru> (raw)
In-Reply-To: <20111109103432.GA27378@linux-mips.org>
On 09.11.2011 14:34, Ralf Baechle wrote:
> Hmm... Looking at the R4000 manual which generall has the longest
> pipeline hazards, mtc0 gets executed at stage 7, interrupts get sampled
> at stage 3 meaning there is a (7 - 3 - 1) = 3 cycles hazard. Does
> that one statisfy your constraints? Or are additional cycles needed
> for a hazard that's generated outside of the CPU's pipeline?
In fact, current back_to_back_hazard is more than enough for cpus I deal
with. I guess, required time to wait equals number of stages between EX
(or RD) and WB stages for modern cpus, because CP0 CAUSE is updated
during WB nowadays.
I suspect, the time required to update internal counter logic for
original r4k might be bigger though. At least old code waited 12 cycles
(4*irq_disable_hazard which is 3 for r4k). Perhaps, we should keep this
code and insert the same amount of nops for old cpus at least.
Regards,
Gleb.
prev parent reply other threads:[~2011-11-09 11:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-08 14:59 [PATCH] MIPS: Kernel hangs occasionally during boot Al Cooper
2011-11-08 17:55 ` Ralf Baechle
2011-11-09 7:40 ` Gleb O. Raiko
2011-11-09 9:13 ` Ralf Baechle
2011-11-09 10:34 ` Ralf Baechle
2011-11-09 11:26 ` Gleb O. Raiko [this message]
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=4EBA6368.6030503@niisi.msk.ru \
--to=raiko@niisi.msk.ru \
--cc=alcooperx@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@linux-mips.org \
--cc=ralf@linux-mips.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.