[Patch] powerpc/cell: make ptcal more reliable (V2)
===
This is for QS21. The following patch allocates pages only from
the specified node, moves the ptcal area into the middle of the
allocated page to avoid potential prefetch problems and prints
the address of the ptcal area to facilitate diagnostics.
Signed-off-by: Gerhard Stenzel
Index: linux-2.6/arch/powerpc/platforms/cell/ras.c
===
--- linux-2.6.orig/arch/powerpc/platforms/cell/ras.c
+++ linux-2.6/arch/powerpc/platforms/cell/ras.c
@@ -122,12 +122,23 @@ static int __init cbe_ptcal_enable_on_no
area->nid = nid;
area->order = order;
- area->pages = alloc_pages_node(area->nid, GFP_KERNEL, area->order);
+ area->pages = alloc_pages_node(area->nid, GFP_KERNEL | GFP_THISNODE,
+ area->order);
- if (!area->pages)
+ if (!area->pages) {
+ printk(KERN_WARNING "%s: no page on node %d\n",
+ __func__, area->nid);
goto out_free_area;
+ }
- addr = __pa(page_address(area->pages));
+ /*
+* We move the ptcal area to the middle of the allocated
+* page, in order to avoid prefetches in memcpy and similar
+* functions stepping on it.
+*/
+ addr = __pa(page_address(area->pages)) + (PAGE_SIZE >> 1);
+ printk(KERN_DEBUG "%s: enabling PTCAL on node %d address=0x%016lx\n",
+ __func__, area->nid, addr);
ret = -EIO;
if (rtas_call(ptcal_start_tok, 3, 1, NULL, area->nid,
=======
Best regards,
Gerhard Stenzel, Linux on Cell Development, LTC
-
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Vorsitzender des Aufsichtsrats: Martin Jetter | Geschaeftsfuehrung: Erich Baier
Sitz der Gesellschaft: Boeblingen | Registergericht: Amtsgericht Stuttgart, HRB
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Re: [Patch] powerpc/cell: make ptcal more reliable
Jeremy Kerr wrote on 05/05/2009 02:57:18 AM:
> Hi Gerhard,
Jeremy, thanks for your comments
>
> > This is for QS21. The following patch allocates pages only from
> > the specified node, moves the ptcal area into the middle of the
> > allocated page to avoid potential prefetch problems and prints
> > the address of the ptcal area to facilitate diagnostics.
>
> You're seeing prefetches that cross a page boundary?
>
> > - area->pages = alloc_pages_node(area->nid, GFP_KERNEL, area->order);
> > + area->pages = alloc_pages_node(area->nid, GFP_KERNEL |
> > GFP_THISNODE, area->order);
>
> Best to keep this under 80 cols.
ok
>
> >
> > - if (!area->pages)
> > + if (!area->pages) {
> > + printk(KERN_INFO "%s: no page on node %d\n",
> > + __FUNCTION__, area->nid);
> >goto out_free_area;
> > + }
>
> That could probably be a KERN_ERR, as we don't have ptcal enabled on
> that node. Also, I believe __func__ is preferred over __FUNCTION__.
Since this is the default for the kdump kernel in most cases, how about
KERN_WARNING instead.:
>
> > - addr = __pa(page_address(area->pages));
> > + /*
> > +* We move the ptcal area to the middle of the allocated
> > +* page, in order to avoid prefetches in memcpy and similar
> > +* functions stepping on it.
> > +*/
> > + addr = __pa(page_address(area->pages)) + (PAGE_SIZE >> 1);
>
> Minor nitpick, but I think (PAGE_SIZE / 2) better illustrates that
> you're putting the addr in the middle of the page. But either should be
> fine.
ok. I prefer to keep it like this. It should be clear from the comment.
>
> > + printk(KERN_INFO "%s: enabling PTCAL on node %d address=0x%016lx
> > PAGE_SIZE>>1=0x%016lx \n",
> > + __FUNCTION__, area->nid, addr, PAGE_SIZE>>1);
>
> 80 cols again. Can we do this as a pr_debug?
"PAGE_SIZE>>1" can be omitted anyway. Removing it brings it below 80 cols.
Regarding pr_debug, the message should appear only on QS21 where it can be
of interest. So, I would prefer to keep a printk.
>
> Cheers,
>
> Jeremy
Thanks again,
Best regards,
Gerhard Stenzel, Linux on Cell/Hybrid Technologies, LTC
---
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Erich
Baier
Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht Stuttgart,
HRB 243294
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[Patch] powerpc/cell: make ptcal more reliable
This is for QS21. The following patch allocates pages only from
the specified node, moves the ptcal area into the middle of the
allocated page to avoid potential prefetch problems and prints
the address of the ptcal area to facilitate diagnostics.
Signed-off-by: Gerhard Stenzel
Index: linux-2.6/arch/powerpc/platforms/cell/ras.c
===
--- linux-2.6.orig/arch/powerpc/platforms/cell/ras.c
+++ linux-2.6/arch/powerpc/platforms/cell/ras.c
@@ -122,12 +122,22 @@ static int __init cbe_ptcal_enable_on_no
area->nid = nid;
area->order = order;
- area->pages = alloc_pages_node(area->nid, GFP_KERNEL, area->order);
+ area->pages = alloc_pages_node(area->nid, GFP_KERNEL | GFP_THISNODE,
area->order);
- if (!area->pages)
+ if (!area->pages) {
+ printk(KERN_INFO "%s: no page on node %d\n",
+ __FUNCTION__, area->nid);
goto out_free_area;
+ }
- addr = __pa(page_address(area->pages));
+ /*
+* We move the ptcal area to the middle of the allocated
+* page, in order to avoid prefetches in memcpy and similar
+* functions stepping on it.
+*/
+ addr = __pa(page_address(area->pages)) + (PAGE_SIZE >> 1);
+ printk(KERN_INFO "%s: enabling PTCAL on node %d address=0x%016lx
PAGE_SIZE>>1=0x%016lx \n",
+ __FUNCTION__, area->nid, addr, PAGE_SIZE>>1);
ret = -EIO;
if (rtas_call(ptcal_start_tok, 3, 1, NULL, area->nid,
=======
Best regards,
Gerhard Stenzel, Linux on Cell Development, LTC
-
IBM Deutschland Entwicklung GmbH
Vorsitzender des Aufsichtsrats: Martin Jetter | Geschaeftsfuehrung: Erich Baier
Sitz der Gesellschaft: Boeblingen | Registergericht: Amtsgericht Stuttgart, HRB
243294
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