Heiko Schocher <h...@denx.de> wrote on 2011/01/21 07:53:02:
> Hello Joakim,
>
> Joakim Tjernlund wrote:
> >> Sent by:
> >> linuxppc-dev-bounces+joakim.tjernlund=transmode...@lists.ozlabs.org
> >>
> >> Rafael Beims <rbe...@gmail.com> wrote on 2011/01/10 17:35:38:
> >>>> Once you have tested it and it works, please send a patch to remove the
> >>>> 8xx workaround.
> >>>> Make sure Scott is cc:ed
> >>>>
> >>>>
> >>> I tested linux-2.6.33 on my ppc880 board today, and even without the
> >>> slowdown.patch applied, the board runs processes with good
> >>> performance.
> >>> It really seems that the problem is solved from linux-2.6.33 on.
> >>>
> >>> I'm not sure what you mean by sending a patch to remove the
> >>> workaround. The only thing that I did in the 2.6.32 version was to
> >>> apply the slowdown.patch attached in the message from Michael.
> >>>
> >>> Could you clarify please?
> >> Yes, this part in arch/powerpc/mm/pgtable.c:
> >> #ifdef CONFIG_8xx
> >> /* On 8xx, cache control instructions (particularly
> >> * "dcbst" from flush_dcache_icache) fault as write
> >> * operation if there is an unpopulated TLB entry
> >> * for the address in question. To workaround that,
> >> * we invalidate the TLB here, thus avoiding dcbst
> >> * misbehaviour.
> >> */
> >> /* 8xx doesn't care about PID, size or ind args */
> >> _tlbil_va(addr, 0, 0, 0);
> >> #endif /* CONFIG_8xx */
> >>
> >> Should be removed in >= 2.6.33 kernels.
> >> My 8xx TLB work fixes this problem more efficiently.
> >
> > Can you test these 2 patches on recent 2.6 linux:
> >>From 9024200169bf86b4f34cb3b1ebf68e0056237bc0 Mon Sep 17 00:00:00 2001
> > From: Joakim Tjernlund <joakim.tjernl...@transmode.se>
> > Date: Tue, 11 Jan 2011 13:43:42 +0100
> > Subject: [PATCH 1/2] powerpc: Move 8xx invalidation of non present TLBs
> [...]
> > and
> >
> >>From 0ef93601290a75b087495dddeee6062a870f1dc6 Mon Sep 17 00:00:00 2001
> > From: Joakim Tjernlund <joakim.tjernl...@transmode.se>
> > Date: Tue, 11 Jan 2011 13:55:22 +0100
> > Subject: [PATCH 2/2] powerpc: Remove 8xx redundant dcbst workaround.
>
> Tested this on a board similliar to the mainline tqm8xx board with
> lmbench:
>
> -bash-3.2# cat /proc/cpuinfo
> processor : 0
> cpu : 8xx
> clock : 80.000000MHz
> revision : 0.0 (pvr 0050 0000)
> bogomips : 10.00
> timebase : 5000000
> platform : KUP4K
> model : KUP4K
> Memory : 96 MB
> -bash-3.2#
>
> -bash-3.2# cat /proc/version
> Linux version 2.6.34-00064-g3e81b6b (h...@pollux.denx.de) (gcc version 4.2.2)
> #89 Thu Jan 20 08:39:52 CET 2011
> -bash-3.2#
>
> (First run of lmbench without your 2 patches, the two other runs with it)
Thanks,
>From a quick look, the only thing that really stands out is Prot Fault below:
> File & VM system latencies in microseconds - smaller is better
> -------------------------------------------------------------------------------
> Host OS 0K File 10K File Mmap Prot Page
> 100fd
> Create Delete Create Delete Latency Fault Fault
> selct
> --------- ------------- ------ ------ ------ ------ ------- ----- -------
> -----
> kup4k Linux 2.6.34- 16.7K 10.3K 90.9K 13.7K 22.6K 27.1 43.4
> 117.9
> kup4k Linux 2.6.34- 16.9K 15.6K 100.0K 16.1K 22.7K 9.590 39.8
> 119.2
> kup4k Linux 2.6.34- 16.7K 13.5K 100.0K 15.9K 22.8K 9.306 39.8
> 119.6
Anyhow, nothing broke so I am happy with the results.
On top of those 2 patches I came up with this cleanup patch too:
>From 920c236b290ee00d84506369e3898126c78215e8 Mon Sep 17 00:00:00 2001
From: Joakim Tjernlund <joakim.tjernl...@transmode.se>
Date: Tue, 18 Jan 2011 09:50:09 +0100
Subject: [PATCH 3/3] powerpc: Use symbolic constants in 8xx TLB asm
Use the PTE #defines where possible instead of
hardcoded constants.
Signed-off-by: Joakim Tjernlund <joakim.tjernl...@transmode.se>
---
arch/powerpc/kernel/head_8xx.S | 10 +++++-----
1 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 6cd99e2..31ed813 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -451,11 +451,11 @@ DataStoreTLBMiss:
* this into the Linux pgd/pmd and load it in the operation
* above.
*/
- rlwimi r11, r10, 0, 27, 27
+ rlwimi r11, r10, 0, _PAGE_GUARDED
/* Insert the WriteThru flag into the TWC from the Linux PTE.
* It is bit 25 in the Linux PTE and bit 30 in the TWC
*/
- rlwimi r11, r10, 32-5, 30, 30
+ rlwimi r11, r10, 32-5, _PAGE_WRITETHRU>>5
DO_8xx_CPU6(0x3b80, r3)
mtspr SPRN_MD_TWC, r11
@@ -474,10 +474,10 @@ DataStoreTLBMiss:
rlwimi r10, r11, 0, _PAGE_PRESENT
#endif
/* Honour kernel RO, User NA */
- /* 0x200 == Extended encoding, bit 22 */
- rlwimi r10, r10, 32-2, 0x200 /* Copy USER to bit 22, 0x200 */
+ /* 0x200 == Encoding, bit 22 */
+ rlwimi r10, r10, 32-2, _PAGE_USER>>2 /* Copy USER to Encoding */
/* r11 = (r10 & _PAGE_RW) >> 1 */
- rlwinm r11, r10, 32-1, 0x200
+ rlwinm r11, r10, 32-1, _PAGE_RW>>1
or r10, r11, r10
/* invert RW and 0x200 bits */
xori r10, r10, _PAGE_RW | 0x200
--
1.7.3.4
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