From: Peter Korsgaard <jacmet@sunsite•dk>
To: Grant Likely <grant.likely@secretlab•ca>
Cc: linuxppc-dev@ozlabs•org, paulus@samba•org,
David Gibson <david@gibson•dropbear.id.au>
Subject: Re: [PATCH 4/4] Uartlite: speed up console output
Date: Wed, 31 Oct 2007 15:45:02 +0100 [thread overview]
Message-ID: <87mytz4a35.fsf@macbook.be.48ers.dk> (raw)
In-Reply-To: <20071023042746.30309.15188.stgit@trillian.cg.shawcable.net> (Grant Likely's message of "Mon\, 22 Oct 2007 22\:27\:46 -0600")
>>>>> "Grant" == Grant Likely <grant.likely@secretlab•ca> writes:
Hi,
Grant> From: Grant Likely <grant.likely@secretlab•ca>
Grant> Change the wait_tx routine to call cpu_relax() instead of udelay() to
Grant> reduce console output latency and test for the TXFULL bit instead of
Grant> TXEMPTY. That way the FIFO doesn't need to by 100% flushed before
Grant> writing the next character.
Sorry for the slow response - I had a misunderstanding with the
phone company, and I'm now without inet :/
Looks good to me. I gave it a quick spin to check the speed
difference:
Old:
[ 0.453101] Freeing unused kernel memory: 52k init
New:
[ 0.433686] Freeing unused kernel memory: 52k init
So it shaves off ~20ms (~4%) of bootup.
It ofcause means that the console routines return before the data is
actually transmitted on the wire, but I guess you have to screw
seriously up for the UART to die before emptying it's FIFO.
Grant> Signed-off-by: Grant Likely <grant.likely@secretlab•ca>
Acked-by: Peter Korsgaard <jacmet@sunsite•dk>
--
Bye, Peter Korsgaard
prev parent reply other threads:[~2007-10-31 14:45 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-23 4:27 [PATCH 0/4] Misc patches for the 2.6.24 merge window Grant Likely
2007-10-23 4:27 ` [PATCH 1/4] bootwrapper: Allow wrapper script to execute verbosely Grant Likely
2007-10-23 4:27 ` [PATCH 2/4] bootwrapper: Bail from script if any command fails Grant Likely
2007-10-23 4:27 ` [PATCH 3/4] Device tree bindings for Xilinx devices Grant Likely
2007-10-23 12:36 ` Josh Boyer
2007-10-23 4:27 ` [PATCH 4/4] Uartlite: speed up console output Grant Likely
2007-10-31 14:45 ` Peter Korsgaard [this message]
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