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| Started by | Vineet Gupta <Vineet.Gupta1@synopsys.com> |
|---|---|
| First post | 2015-09-29 10:00 +0200 |
| Last post | 2015-10-03 12:20 +0200 |
| Articles | 6 — 4 participants |
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[PATCH] mm: optimize PageHighMem() check Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2015-09-29 10:00 +0200
Re: [PATCH] mm: optimize PageHighMem() check Michal Hocko <mhocko@kernel.org> - 2015-10-01 15:20 +0200
Re: [PATCH] mm: optimize PageHighMem() check Andrew Morton <akpm@linux-foundation.org> - 2015-10-02 01:30 +0200
Re: [PATCH] mm: optimize PageHighMem() check Vineet Gupta <vgupta@synopsys.com> - 2015-10-02 09:20 +0200
Re: [PATCH] mm: optimize PageHighMem() check Andrew Morton <akpm@linux-foundation.org> - 2015-10-02 23:00 +0200
Re: [PATCH] mm: optimize PageHighMem() check Vineet Gupta <Vineet.Gupta1@synopsys.com> - 2015-10-03 12:20 +0200
| From | Vineet Gupta <Vineet.Gupta1@synopsys.com> |
|---|---|
| Date | 2015-09-29 10:00 +0200 |
| Subject | [PATCH] mm: optimize PageHighMem() check |
| Message-ID | <qdXZo-ds-19@gated-at.bofh.it> |
This came up when implementing HIHGMEM/PAE40 for ARC.
The kmap() / kmap_atomic() generated code seemed needlessly bloated due
to the way PageHighMem() macro is implemented.
It derives the exact zone for page and then does pointer subtraction
with first zone to infer the zone_type.
The pointer arithmatic in turn generates the code bloat.
PageHighMem(page)
is_highmem(page_zone(page))
zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones
Instead use is_highmem_idx() to work on zone_type available in page flags
----- Before -----
80756348: mov_s r13,r0
8075634a: ld_s r2,[r13,0]
8075634c: lsr_s r2,r2,30
8075634e: mpy r2,r2,0x2a4
80756352: add_s r2,r2,0x80aef880
80756358: ld_s r3,[r2,28]
8075635a: sub_s r2,r2,r3
8075635c: breq r2,0x2a4,80756378 <kmap+0x48>
80756364: breq r2,0x548,80756378 <kmap+0x48>
----- After -----
80756330: mov_s r13,r0
80756332: ld_s r2,[r13,0]
80756334: lsr_s r2,r2,30
80756336: sub_s r2,r2,1
80756338: brlo r2,2,80756348 <kmap+0x30>
For x86 defconfig build (32 bit only) it saves around 900 bytes.
For ARC defconfig with HIGHMEM, it saved around 2K bytes.
---->8-------
./scripts/bloat-o-meter x86/vmlinux-defconfig-pre x86/vmlinux-defconfig-post
add/remove: 0/0 grow/shrink: 0/36 up/down: 0/-934 (-934)
function old new delta
saveable_page 162 154 -8
saveable_highmem_page 154 146 -8
skb_gro_reset_offset 147 131 -16
...
...
__change_page_attr_set_clr 1715 1678 -37
setup_data_read 434 394 -40
mon_bin_event 1967 1927 -40
swsusp_save 1148 1105 -43
_set_pages_array 549 493 -56
---->8-------
e.g. For ARC kmap()
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jennifer Herbert <jennifer.herbert@citrix.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
include/linux/page-flags.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 41c93844fb1d..2953aaa06d67 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -252,7 +252,7 @@ PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim)
* Must use a macro here due to header dependency issues. page_zone() is not
* available at this point.
*/
-#define PageHighMem(__p) is_highmem(page_zone(__p))
+#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
#else
PAGEFLAG_FALSE(HighMem)
#endif
--
1.9.1
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| From | Michal Hocko <mhocko@kernel.org> |
|---|---|
| Date | 2015-10-01 15:20 +0200 |
| Message-ID | <qeLW9-5iU-3@gated-at.bofh.it> |
| In reply to | #1234790 |
On Tue 29-09-15 13:24:20, Vineet Gupta wrote: > This came up when implementing HIHGMEM/PAE40 for ARC. > The kmap() / kmap_atomic() generated code seemed needlessly bloated due > to the way PageHighMem() macro is implemented. > It derives the exact zone for page and then does pointer subtraction > with first zone to infer the zone_type. > The pointer arithmatic in turn generates the code bloat. > > PageHighMem(page) > is_highmem(page_zone(page)) > zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones > > Instead use is_highmem_idx() to work on zone_type available in page flags > > ----- Before ----- > 80756348: mov_s r13,r0 > 8075634a: ld_s r2,[r13,0] > 8075634c: lsr_s r2,r2,30 > 8075634e: mpy r2,r2,0x2a4 > 80756352: add_s r2,r2,0x80aef880 > 80756358: ld_s r3,[r2,28] > 8075635a: sub_s r2,r2,r3 > 8075635c: breq r2,0x2a4,80756378 <kmap+0x48> > 80756364: breq r2,0x548,80756378 <kmap+0x48> > > ----- After ----- > 80756330: mov_s r13,r0 > 80756332: ld_s r2,[r13,0] > 80756334: lsr_s r2,r2,30 > 80756336: sub_s r2,r2,1 > 80756338: brlo r2,2,80756348 <kmap+0x30> > > For x86 defconfig build (32 bit only) it saves around 900 bytes. > For ARC defconfig with HIGHMEM, it saved around 2K bytes. > > ---->8------- > ./scripts/bloat-o-meter x86/vmlinux-defconfig-pre x86/vmlinux-defconfig-post > add/remove: 0/0 grow/shrink: 0/36 up/down: 0/-934 (-934) > function old new delta > saveable_page 162 154 -8 > saveable_highmem_page 154 146 -8 > skb_gro_reset_offset 147 131 -16 > ... > ... > __change_page_attr_set_clr 1715 1678 -37 > setup_data_read 434 394 -40 > mon_bin_event 1967 1927 -40 > swsusp_save 1148 1105 -43 > _set_pages_array 549 493 -56 > ---->8------- > > e.g. For ARC kmap() > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> > Cc: Hugh Dickins <hughd@google.com> > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > Cc: Michal Hocko <mhocko@suse.cz> > Cc: Jennifer Herbert <jennifer.herbert@citrix.com> > Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Looks reasonably to me. Acked-by: Michal Hocko <mhocko@suse.com> > --- > include/linux/page-flags.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h > index 41c93844fb1d..2953aaa06d67 100644 > --- a/include/linux/page-flags.h > +++ b/include/linux/page-flags.h > @@ -252,7 +252,7 @@ PAGEFLAG(Readahead, reclaim) TESTCLEARFLAG(Readahead, reclaim) > * Must use a macro here due to header dependency issues. page_zone() is not > * available at this point. > */ > -#define PageHighMem(__p) is_highmem(page_zone(__p)) > +#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p)) > #else > PAGEFLAG_FALSE(HighMem) > #endif > -- > 1.9.1 -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Andrew Morton <akpm@linux-foundation.org> |
|---|---|
| Date | 2015-10-02 01:30 +0200 |
| Message-ID | <qeVsu-2zB-9@gated-at.bofh.it> |
| In reply to | #1234790 |
On Tue, 29 Sep 2015 13:24:20 +0530 Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote: > This came up when implementing HIHGMEM/PAE40 for ARC. > The kmap() / kmap_atomic() generated code seemed needlessly bloated due > to the way PageHighMem() macro is implemented. > It derives the exact zone for page and then does pointer subtraction > with first zone to infer the zone_type. > The pointer arithmatic in turn generates the code bloat. > > PageHighMem(page) > is_highmem(page_zone(page)) > zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones > > Instead use is_highmem_idx() to work on zone_type available in page flags > > ----- Before ----- > 80756348: mov_s r13,r0 > 8075634a: ld_s r2,[r13,0] > 8075634c: lsr_s r2,r2,30 > 8075634e: mpy r2,r2,0x2a4 > 80756352: add_s r2,r2,0x80aef880 > 80756358: ld_s r3,[r2,28] > 8075635a: sub_s r2,r2,r3 > 8075635c: breq r2,0x2a4,80756378 <kmap+0x48> > 80756364: breq r2,0x548,80756378 <kmap+0x48> > > ----- After ----- > 80756330: mov_s r13,r0 > 80756332: ld_s r2,[r13,0] > 80756334: lsr_s r2,r2,30 > 80756336: sub_s r2,r2,1 > 80756338: brlo r2,2,80756348 <kmap+0x30> > > For x86 defconfig build (32 bit only) it saves around 900 bytes. > For ARC defconfig with HIGHMEM, it saved around 2K bytes. > > ---->8------- > ./scripts/bloat-o-meter x86/vmlinux-defconfig-pre x86/vmlinux-defconfig-post > add/remove: 0/0 grow/shrink: 0/36 up/down: 0/-934 (-934) > function old new delta > saveable_page 162 154 -8 > saveable_highmem_page 154 146 -8 > skb_gro_reset_offset 147 131 -16 > ... > ... > __change_page_attr_set_clr 1715 1678 -37 > setup_data_read 434 394 -40 > mon_bin_event 1967 1927 -40 > swsusp_save 1148 1105 -43 > _set_pages_array 549 493 -56 > ---->8------- > > e.g. For ARC kmap() > is_highmem() is deranged. Can't we use a bit in zone->flags or something? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Vineet Gupta <vgupta@synopsys.com> |
|---|---|
| Date | 2015-10-02 09:20 +0200 |
| Message-ID | <qf2Nl-4OQ-39@gated-at.bofh.it> |
| In reply to | #1237829 |
On Friday 02 October 2015 04:55 AM, Andrew Morton wrote: > On Tue, 29 Sep 2015 13:24:20 +0530 Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote: > >> > This came up when implementing HIHGMEM/PAE40 for ARC. >> > The kmap() / kmap_atomic() generated code seemed needlessly bloated due >> > to the way PageHighMem() macro is implemented. >> > It derives the exact zone for page and then does pointer subtraction >> > with first zone to infer the zone_type. >> > The pointer arithmatic in turn generates the code bloat. >> > >> > PageHighMem(page) >> > is_highmem(page_zone(page)) >> > zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones >> > >> > Instead use is_highmem_idx() to work on zone_type available in page flags >> > >> > ----- Before ----- >> > 80756348: mov_s r13,r0 >> > 8075634a: ld_s r2,[r13,0] >> > 8075634c: lsr_s r2,r2,30 >> > 8075634e: mpy r2,r2,0x2a4 >> > 80756352: add_s r2,r2,0x80aef880 >> > 80756358: ld_s r3,[r2,28] >> > 8075635a: sub_s r2,r2,r3 >> > 8075635c: breq r2,0x2a4,80756378 <kmap+0x48> >> > 80756364: breq r2,0x548,80756378 <kmap+0x48> >> > >> > ----- After ----- >> > 80756330: mov_s r13,r0 >> > 80756332: ld_s r2,[r13,0] >> > 80756334: lsr_s r2,r2,30 >> > 80756336: sub_s r2,r2,1 >> > 80756338: brlo r2,2,80756348 <kmap+0x30> >> > >> > For x86 defconfig build (32 bit only) it saves around 900 bytes. >> > For ARC defconfig with HIGHMEM, it saved around 2K bytes. >> > >> > ---->8------- >> > ./scripts/bloat-o-meter x86/vmlinux-defconfig-pre x86/vmlinux-defconfig-post >> > add/remove: 0/0 grow/shrink: 0/36 up/down: 0/-934 (-934) >> > function old new delta >> > saveable_page 162 154 -8 >> > saveable_highmem_page 154 146 -8 >> > skb_gro_reset_offset 147 131 -16 >> > ... >> > ... >> > __change_page_attr_set_clr 1715 1678 -37 >> > setup_data_read 434 394 -40 >> > mon_bin_event 1967 1927 -40 >> > swsusp_save 1148 1105 -43 >> > _set_pages_array 549 493 -56 >> > ---->8------- >> > >> > e.g. For ARC kmap() >> > > is_highmem() is deranged. Can't we use a bit in zone->flags or > something? It won't be "a" bit since zone_type is an enum. However zone->flags could be split into 2 bitfields to hold enum zone_flags and enum zone_type. However this patch still is independent of that since we have struct page as starting point and zone_type is available from there directly w/o monkeying around with any zone structs. -Vineet -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Andrew Morton <akpm@linux-foundation.org> |
|---|---|
| Date | 2015-10-02 23:00 +0200 |
| Message-ID | <qffAS-6a6-11@gated-at.bofh.it> |
| In reply to | #1238002 |
On Fri, 2 Oct 2015 12:45:53 +0530 Vineet Gupta <vgupta@synopsys.com> wrote:
> On Friday 02 October 2015 04:55 AM, Andrew Morton wrote:
> > On Tue, 29 Sep 2015 13:24:20 +0530 Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote:
> >
> >> > This came up when implementing HIHGMEM/PAE40 for ARC.
> >> > The kmap() / kmap_atomic() generated code seemed needlessly bloated due
> >> > to the way PageHighMem() macro is implemented.
> >> > It derives the exact zone for page and then does pointer subtraction
> >> > with first zone to infer the zone_type.
> >> > The pointer arithmatic in turn generates the code bloat.
> >> >
> >> > PageHighMem(page)
> >> > is_highmem(page_zone(page))
> >> > zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones
> >> >
> >> > Instead use is_highmem_idx() to work on zone_type available in page flags
> >> >
> >> > ----- Before -----
> >> > 80756348: mov_s r13,r0
> >> > 8075634a: ld_s r2,[r13,0]
> >> > 8075634c: lsr_s r2,r2,30
> >> > 8075634e: mpy r2,r2,0x2a4
> >> > 80756352: add_s r2,r2,0x80aef880
> >> > 80756358: ld_s r3,[r2,28]
> >> > 8075635a: sub_s r2,r2,r3
> >> > 8075635c: breq r2,0x2a4,80756378 <kmap+0x48>
> >> > 80756364: breq r2,0x548,80756378 <kmap+0x48>
> >> >
> >> > ----- After -----
> >> > 80756330: mov_s r13,r0
> >> > 80756332: ld_s r2,[r13,0]
> >> > 80756334: lsr_s r2,r2,30
> >> > 80756336: sub_s r2,r2,1
> >> > 80756338: brlo r2,2,80756348 <kmap+0x30>
> >> >
> >> > For x86 defconfig build (32 bit only) it saves around 900 bytes.
> >> > For ARC defconfig with HIGHMEM, it saved around 2K bytes.
> >> >
> >> > ---->8-------
> >> > ./scripts/bloat-o-meter x86/vmlinux-defconfig-pre x86/vmlinux-defconfig-post
> >> > add/remove: 0/0 grow/shrink: 0/36 up/down: 0/-934 (-934)
> >> > function old new delta
> >> > saveable_page 162 154 -8
> >> > saveable_highmem_page 154 146 -8
> >> > skb_gro_reset_offset 147 131 -16
> >> > ...
> >> > ...
> >> > __change_page_attr_set_clr 1715 1678 -37
> >> > setup_data_read 434 394 -40
> >> > mon_bin_event 1967 1927 -40
> >> > swsusp_save 1148 1105 -43
> >> > _set_pages_array 549 493 -56
> >> > ---->8-------
> >> >
> >> > e.g. For ARC kmap()
> >> >
> > is_highmem() is deranged. Can't we use a bit in zone->flags or
> > something?
>
> It won't be "a" bit since zone_type is an enum.
Yes it will!
static inline int is_highmem(struct zone *zone)
{
return test_bit(ZONE_HIGHMEM, &zone->flags);
}
> ...
>
> However this patch still is independent of that since we have struct page as
> starting point and zone_type is available from there directly w/o monkeying around
> with any zone structs.
yup.
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| From | Vineet Gupta <Vineet.Gupta1@synopsys.com> |
|---|---|
| Date | 2015-10-03 12:20 +0200 |
| Message-ID | <qfs54-7j6-13@gated-at.bofh.it> |
| In reply to | #1238609 |
On Saturday 03 October 2015 02:23 AM, Andrew Morton wrote:
> On Fri, 2 Oct 2015 12:45:53 +0530 Vineet Gupta <vgupta@synopsys.com> wrote:
>
>> On Friday 02 October 2015 04:55 AM, Andrew Morton wrote:
>>> On Tue, 29 Sep 2015 13:24:20 +0530 Vineet Gupta <Vineet.Gupta1@synopsys.com> wrote:
>>>
>>>>> This came up when implementing HIHGMEM/PAE40 for ARC.
>>>>> The kmap() / kmap_atomic() generated code seemed needlessly bloated due
>>>>> to the way PageHighMem() macro is implemented.
>>>>> It derives the exact zone for page and then does pointer subtraction
>>>>> with first zone to infer the zone_type.
>>>>> The pointer arithmatic in turn generates the code bloat.
>>>>>
>>>>> PageHighMem(page)
>>>>> is_highmem(page_zone(page))
>>>>> zone_off = (char *)zone - (char *)zone->zone_pgdat->node_zones
>>>>>
>>>>> Instead use is_highmem_idx() to work on zone_type available in page flags
>>>>>
>>>>> ----- Before -----
>>>>> 80756348: mov_s r13,r0
>>>>> 8075634a: ld_s r2,[r13,0]
>>>>> 8075634c: lsr_s r2,r2,30
>>>>> 8075634e: mpy r2,r2,0x2a4
>>>>> 80756352: add_s r2,r2,0x80aef880
>>>>> 80756358: ld_s r3,[r2,28]
>>>>> 8075635a: sub_s r2,r2,r3
>>>>> 8075635c: breq r2,0x2a4,80756378 <kmap+0x48>
>>>>> 80756364: breq r2,0x548,80756378 <kmap+0x48>
>>>>>
>>>>> ----- After -----
>>>>> 80756330: mov_s r13,r0
>>>>> 80756332: ld_s r2,[r13,0]
>>>>> 80756334: lsr_s r2,r2,30
>>>>> 80756336: sub_s r2,r2,1
>>>>> 80756338: brlo r2,2,80756348 <kmap+0x30>
>>>>>
>>>>> For x86 defconfig build (32 bit only) it saves around 900 bytes.
>>>>> For ARC defconfig with HIGHMEM, it saved around 2K bytes.
>>>>>
>>>>> ---->8-------
>>>>> ./scripts/bloat-o-meter x86/vmlinux-defconfig-pre x86/vmlinux-defconfig-post
>>>>> add/remove: 0/0 grow/shrink: 0/36 up/down: 0/-934 (-934)
>>>>> function old new delta
>>>>> saveable_page 162 154 -8
>>>>> saveable_highmem_page 154 146 -8
>>>>> skb_gro_reset_offset 147 131 -16
>>>>> ...
>>>>> ...
>>>>> __change_page_attr_set_clr 1715 1678 -37
>>>>> setup_data_read 434 394 -40
>>>>> mon_bin_event 1967 1927 -40
>>>>> swsusp_save 1148 1105 -43
>>>>> _set_pages_array 549 493 -56
>>>>> ---->8-------
>>>>>
>>>>> e.g. For ARC kmap()
>>>>>
>>> is_highmem() is deranged. Can't we use a bit in zone->flags or
>>> something?
>> It won't be "a" bit since zone_type is an enum.
> Yes it will!
>
> static inline int is_highmem(struct zone *zone)
> {
> return test_bit(ZONE_HIGHMEM, &zone->flags);
> }
Point is do we want to fix this specific case, or do we want to improve zone_idx()
in general.
#define zone_idx(zone) ((zone) - (zone)->zone_pgdat->node_zones
If former, I can split up zone->flags into 31:1 bit-field. Otherwise I will split
it into 24:8 to hold both zone_flags and zone_type
>> ...
>>
>> However this patch still is independent of that since we have struct page as
>> starting point and zone_type is available from there directly w/o monkeying around
>> with any zone structs.
> yup.
Do u want me to carry this as part of the the ARC HIGHMEM/PAE40 patchset or would
you rather prefer merging it via mm tree.
Thx,
-Vineet
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