* [PATCH] x86/head64: micro optimization: use memset instead of for loop
@ 2016-01-30 8:01 Alexander Kuleshov
2016-01-30 8:26 ` [tip:x86/boot] x86/boot: Micro-optimize reset_early_page_tables() tip-bot for Alexander Kuleshov
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Kuleshov @ 2016-01-30 8:01 UTC (permalink / raw)
To: Thomas Gleixner
Cc: Ingo Molnar, H . Peter Anvin, Andy Lutomirski, Andrey Ryabinin,
Alexander Popov, x86, linux-kernel, Alexander Kuleshov
This patch simplifies clearing of page table directories, by
the using of the fast memset() from the arch/x86/lib/memset_64.S.
Besides this, we 25 bytes is 25 bytes less than original.
text data bss dec hex filename
9735144 4970776 15474688 30180608 1cc8500 vmlinux.old
9735119 4970776 15474688 30180583 1cc84e7 vmlinux
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
arch/x86/kernel/head64.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index f129a9a..4260ac4 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -40,13 +40,8 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
/* Wipe all early page tables except for the kernel symbol map */
static void __init reset_early_page_tables(void)
{
- unsigned long i;
-
- for (i = 0; i < PTRS_PER_PGD-1; i++)
- early_level4_pgt[i].pgd = 0;
-
+ memset(early_level4_pgt, 0, sizeof(pgd_t) * (PTRS_PER_PGD-1));
next_early_pgt = 0;
-
write_cr3(__pa_nodebug(early_level4_pgt));
}
@@ -54,7 +49,6 @@ static void __init reset_early_page_tables(void)
int __init early_make_pgtable(unsigned long address)
{
unsigned long physaddr = address - __PAGE_OFFSET;
- unsigned long i;
pgdval_t pgd, *pgd_p;
pudval_t pud, *pud_p;
pmdval_t pmd, *pmd_p;
@@ -81,8 +75,7 @@ again:
}
pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
- for (i = 0; i < PTRS_PER_PUD; i++)
- pud_p[i] = 0;
+ memset(pud_p, 0, sizeof(pud_p) * PTRS_PER_PUD);
*pgd_p = (pgdval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
}
pud_p += pud_index(address);
@@ -97,8 +90,7 @@ again:
}
pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
- for (i = 0; i < PTRS_PER_PMD; i++)
- pmd_p[i] = 0;
+ memset(pmd_p, 0, sizeof(pmd_p) * PTRS_PER_PMD);
*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
}
pmd = (physaddr & PMD_MASK) + early_pmd_flags;
--
2.7.0.25.gfc10eb5
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [tip:x86/boot] x86/boot: Micro-optimize reset_early_page_tables()
2016-01-30 8:01 [PATCH] x86/head64: micro optimization: use memset instead of for loop Alexander Kuleshov
@ 2016-01-30 8:26 ` tip-bot for Alexander Kuleshov
2016-02-05 0:25 ` Yinghai Lu
0 siblings, 1 reply; 6+ messages in thread
From: tip-bot for Alexander Kuleshov @ 2016-01-30 8:26 UTC (permalink / raw)
To: linux-tip-commits
Cc: kuleshovmail, linux-kernel, tglx, hpa, mingo, torvalds, luto,
alpopov, peterz, ryabinin.a.a
Commit-ID: 5e9ebbd87a99ecc6abb74325b0ac63c46891f6f3
Gitweb: http://git.kernel.org/tip/5e9ebbd87a99ecc6abb74325b0ac63c46891f6f3
Author: Alexander Kuleshov <kuleshovmail@gmail.com>
AuthorDate: Sat, 30 Jan 2016 14:01:12 +0600
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Sat, 30 Jan 2016 09:20:55 +0100
x86/boot: Micro-optimize reset_early_page_tables()
Save 25 bytes of code and make the bootup a tiny bit faster:
text data bss dec filename
9735144 4970776 15474688 30180608 vmlinux.old
9735119 4970776 15474688 30180583 vmlinux
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1454140872-16926-1-git-send-email-kuleshovmail@gmail.com
[ Fixed various small details. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/head64.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index f129a9a..35843ca 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -40,13 +40,8 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
/* Wipe all early page tables except for the kernel symbol map */
static void __init reset_early_page_tables(void)
{
- unsigned long i;
-
- for (i = 0; i < PTRS_PER_PGD-1; i++)
- early_level4_pgt[i].pgd = 0;
-
+ memset(early_level4_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
next_early_pgt = 0;
-
write_cr3(__pa_nodebug(early_level4_pgt));
}
@@ -54,7 +49,6 @@ static void __init reset_early_page_tables(void)
int __init early_make_pgtable(unsigned long address)
{
unsigned long physaddr = address - __PAGE_OFFSET;
- unsigned long i;
pgdval_t pgd, *pgd_p;
pudval_t pud, *pud_p;
pmdval_t pmd, *pmd_p;
@@ -81,8 +75,7 @@ again:
}
pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
- for (i = 0; i < PTRS_PER_PUD; i++)
- pud_p[i] = 0;
+ memset(pud_p, 0, sizeof(pud_p) * PTRS_PER_PUD);
*pgd_p = (pgdval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
}
pud_p += pud_index(address);
@@ -97,8 +90,7 @@ again:
}
pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
- for (i = 0; i < PTRS_PER_PMD; i++)
- pmd_p[i] = 0;
+ memset(pmd_p, 0, sizeof(pmd_p) * PTRS_PER_PMD);
*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
}
pmd = (physaddr & PMD_MASK) + early_pmd_flags;
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [tip:x86/boot] x86/boot: Micro-optimize reset_early_page_tables()
2016-01-30 8:26 ` [tip:x86/boot] x86/boot: Micro-optimize reset_early_page_tables() tip-bot for Alexander Kuleshov
@ 2016-02-05 0:25 ` Yinghai Lu
2016-02-09 12:28 ` Ingo Molnar
0 siblings, 1 reply; 6+ messages in thread
From: Yinghai Lu @ 2016-02-05 0:25 UTC (permalink / raw)
To: luto, Ingo Molnar, Linus Torvalds, H. Peter Anvin,
Thomas Gleixner, Linux Kernel Mailing List, Alexander Kuleshov,
ryabinin.a.a, Peter Zijlstra, alpopov
Cc: linux-tip-commits
On Sat, Jan 30, 2016 at 12:26 AM, tip-bot for Alexander Kuleshov
<tipbot@zytor.com> wrote:
> ---
> arch/x86/kernel/head64.c | 14 +++-----------
> 1 file changed, 3 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index f129a9a..35843ca 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -40,13 +40,8 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
.
>
> @@ -54,7 +49,6 @@ static void __init reset_early_page_tables(void)
> int __init early_make_pgtable(unsigned long address)
> {
> unsigned long physaddr = address - __PAGE_OFFSET;
> - unsigned long i;
> pgdval_t pgd, *pgd_p;
> pudval_t pud, *pud_p;
> pmdval_t pmd, *pmd_p;
> @@ -81,8 +75,7 @@ again:
> }
>
> pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
> - for (i = 0; i < PTRS_PER_PUD; i++)
> - pud_p[i] = 0;
> + memset(pud_p, 0, sizeof(pud_p) * PTRS_PER_PUD);
should be
memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
> *pgd_p = (pgdval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
> }
> pud_p += pud_index(address);
> @@ -97,8 +90,7 @@ again:
> }
>
> pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
> - for (i = 0; i < PTRS_PER_PMD; i++)
> - pmd_p[i] = 0;
> + memset(pmd_p, 0, sizeof(pmd_p) * PTRS_PER_PMD);
should be
memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
> *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
> }
> pmd = (physaddr & PMD_MASK) + early_pmd_flags;
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [tip:x86/boot] x86/boot: Micro-optimize reset_early_page_tables()
2016-02-05 0:25 ` Yinghai Lu
@ 2016-02-09 12:28 ` Ingo Molnar
2016-02-09 13:11 ` [PATCH v2] x86/head64: micro optimization: use memset instead of for loop Alexander Kuleshov
0 siblings, 1 reply; 6+ messages in thread
From: Ingo Molnar @ 2016-02-09 12:28 UTC (permalink / raw)
To: Yinghai Lu
Cc: luto, Linus Torvalds, H. Peter Anvin, Thomas Gleixner,
Linux Kernel Mailing List, Alexander Kuleshov, ryabinin.a.a,
Peter Zijlstra, alpopov, linux-tip-commits
* Yinghai Lu <yinghai@kernel.org> wrote:
> On Sat, Jan 30, 2016 at 12:26 AM, tip-bot for Alexander Kuleshov
> <tipbot@zytor.com> wrote:
> > ---
> > arch/x86/kernel/head64.c | 14 +++-----------
> > 1 file changed, 3 insertions(+), 11 deletions(-)
> >
> > diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> > index f129a9a..35843ca 100644
> > --- a/arch/x86/kernel/head64.c
> > +++ b/arch/x86/kernel/head64.c
> > @@ -40,13 +40,8 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
>
> .
> >
> > @@ -54,7 +49,6 @@ static void __init reset_early_page_tables(void)
> > int __init early_make_pgtable(unsigned long address)
> > {
> > unsigned long physaddr = address - __PAGE_OFFSET;
> > - unsigned long i;
> > pgdval_t pgd, *pgd_p;
> > pudval_t pud, *pud_p;
> > pmdval_t pmd, *pmd_p;
> > @@ -81,8 +75,7 @@ again:
> > }
> >
> > pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
> > - for (i = 0; i < PTRS_PER_PUD; i++)
> > - pud_p[i] = 0;
> > + memset(pud_p, 0, sizeof(pud_p) * PTRS_PER_PUD);
>
> should be
> memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
>
> > *pgd_p = (pgdval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
> > }
> > pud_p += pud_index(address);
> > @@ -97,8 +90,7 @@ again:
> > }
> >
> > pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
> > - for (i = 0; i < PTRS_PER_PMD; i++)
> > - pmd_p[i] = 0;
> > + memset(pmd_p, 0, sizeof(pmd_p) * PTRS_PER_PMD);
>
> should be
> memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
Indeed. Fortunately the two sizes are the same AFAICS, but this should
nevertheless be fixed.
Thanks,
Ingo
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2] x86/head64: micro optimization: use memset instead of for loop
2016-02-09 12:28 ` Ingo Molnar
@ 2016-02-09 13:11 ` Alexander Kuleshov
2016-02-09 13:18 ` Ingo Molnar
0 siblings, 1 reply; 6+ messages in thread
From: Alexander Kuleshov @ 2016-02-09 13:11 UTC (permalink / raw)
To: Ingo Molnar, Thomas Gleixner, H . Peter Anvin
Cc: Andrey Ryabinin, Andy Lutomirski, Andy Shevchenko,
Alexander Popov, linux-kernel, Alexander Kuleshov
This patch simplifies clearing of page table directories, by
the using of the fast memset() from the arch/x86/lib/memset_64.S.
Besides this, we 25 bytes is 25 bytes less than original.
text data bss dec hex filename
9735144 4970776 15474688 30180608 1cc8500 vmlinux.old
9735119 4970776 15474688 30180583 1cc84e7 vmlinux
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
Changelog:
v2: We got sizeof pud_p/pmd_p in the v1, but actually we need
to take sizeof of pud_p/pmd_p pointer, although their sizes are
the same.
arch/x86/kernel/head64.c | 14 +++-----------
1 file changed, 3 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 2c0f340..1f4422d 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -40,13 +40,8 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
/* Wipe all early page tables except for the kernel symbol map */
static void __init reset_early_page_tables(void)
{
- unsigned long i;
-
- for (i = 0; i < PTRS_PER_PGD-1; i++)
- early_level4_pgt[i].pgd = 0;
-
+ memset(early_level4_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
next_early_pgt = 0;
-
write_cr3(__pa_nodebug(early_level4_pgt));
}
@@ -54,7 +49,6 @@ static void __init reset_early_page_tables(void)
int __init early_make_pgtable(unsigned long address)
{
unsigned long physaddr = address - __PAGE_OFFSET;
- unsigned long i;
pgdval_t pgd, *pgd_p;
pudval_t pud, *pud_p;
pmdval_t pmd, *pmd_p;
@@ -81,8 +75,7 @@ again:
}
pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
- for (i = 0; i < PTRS_PER_PUD; i++)
- pud_p[i] = 0;
+ memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
*pgd_p = (pgdval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
}
pud_p += pud_index(address);
@@ -97,8 +90,7 @@ again:
}
pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
- for (i = 0; i < PTRS_PER_PMD; i++)
- pmd_p[i] = 0;
+ memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
}
pmd = (physaddr & PMD_MASK) + early_pmd_flags;
--
2.7.0.25.gfc10eb5
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2] x86/head64: micro optimization: use memset instead of for loop
2016-02-09 13:11 ` [PATCH v2] x86/head64: micro optimization: use memset instead of for loop Alexander Kuleshov
@ 2016-02-09 13:18 ` Ingo Molnar
0 siblings, 0 replies; 6+ messages in thread
From: Ingo Molnar @ 2016-02-09 13:18 UTC (permalink / raw)
To: Alexander Kuleshov
Cc: Ingo Molnar, Thomas Gleixner, H . Peter Anvin, Andrey Ryabinin,
Andy Lutomirski, Andy Shevchenko, Alexander Popov, linux-kernel
* Alexander Kuleshov <kuleshovmail@gmail.com> wrote:
> This patch simplifies clearing of page table directories, by
> the using of the fast memset() from the arch/x86/lib/memset_64.S.
> Besides this, we 25 bytes is 25 bytes less than original.
>
> text data bss dec hex filename
>
> 9735144 4970776 15474688 30180608 1cc8500 vmlinux.old
> 9735119 4970776 15474688 30180583 1cc84e7 vmlinux
>
> Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
> ---
> Changelog:
>
> v2: We got sizeof pud_p/pmd_p in the v1, but actually we need
> to take sizeof of pud_p/pmd_p pointer, although their sizes are
> the same.
Please send a delta patch (with changelog) as the v1 commit is already deep within
the tip:x86/boot branch.
Thanks,
Ingo
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-02-09 13:18 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2016-01-30 8:01 [PATCH] x86/head64: micro optimization: use memset instead of for loop Alexander Kuleshov
2016-01-30 8:26 ` [tip:x86/boot] x86/boot: Micro-optimize reset_early_page_tables() tip-bot for Alexander Kuleshov
2016-02-05 0:25 ` Yinghai Lu
2016-02-09 12:28 ` Ingo Molnar
2016-02-09 13:11 ` [PATCH v2] x86/head64: micro optimization: use memset instead of for loop Alexander Kuleshov
2016-02-09 13:18 ` Ingo Molnar
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