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s390/vmemmap: avoid memset(PAGE_UNUSED) when adding consecutive sections

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Let's avoid memset(PAGE_UNUSED) when adding consecutive sections,
whereby the vmemmap of a single section does not span full PMDs.

Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20200722094558.9828-10-david@redhat.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
David Hildenbrand 2020-07-22 11:45:58 +02:00 committed by Heiko Carstens
parent cd5781d63e
commit 2c114df071
1 changed files with 42 additions and 3 deletions
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45
arch/s390/mm/vmem.c
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@ -74,7 +74,22 @@ static void vmem_pte_free(unsigned long *table)
#define PAGE_UNUSED 0xFD
static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
/*
* The unused vmemmap range, which was not yet memset(PAGE_UNUSED) ranges
* from unused_pmd_start to next PMD_SIZE boundary.
*/
static unsigned long unused_pmd_start;
static void vmemmap_flush_unused_pmd(void)
{
if (!unused_pmd_start)
return;
memset(__va(unused_pmd_start), PAGE_UNUSED,
ALIGN(unused_pmd_start, PMD_SIZE) - unused_pmd_start);
unused_pmd_start = 0;
}
static void __vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
{
/*
* As we expect to add in the same granularity as we remove, it's
@ -85,18 +100,41 @@ static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
memset(__va(start), 0, sizeof(struct page));
}
static void vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
{
/*
* We only optimize if the new used range directly follows the
* previously unused range (esp., when populating consecutive sections).
*/
if (unused_pmd_start == start) {
unused_pmd_start = end;
if (likely(IS_ALIGNED(unused_pmd_start, PMD_SIZE)))
unused_pmd_start = 0;
return;
}
vmemmap_flush_unused_pmd();
__vmemmap_use_sub_pmd(start, end);
}
static void vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
{
void *page = __va(ALIGN_DOWN(start, PMD_SIZE));
vmemmap_flush_unused_pmd();
/* Could be our memmap page is filled with PAGE_UNUSED already ... */
vmemmap_use_sub_pmd(start, end);
__vmemmap_use_sub_pmd(start, end);
/* Mark the unused parts of the new memmap page PAGE_UNUSED. */
if (!IS_ALIGNED(start, PMD_SIZE))
memset(page, PAGE_UNUSED, start - __pa(page));
/*
* We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
* consecutive sections. Remember for the last added PMD the last
* unused range in the populated PMD.
*/
if (!IS_ALIGNED(end, PMD_SIZE))
memset(__va(end), PAGE_UNUSED, __pa(page) + PMD_SIZE - end);
unused_pmd_start = end;
}
/* Returns true if the PMD is completely unused and can be freed. */
@ -104,6 +142,7 @@ static bool vmemmap_unuse_sub_pmd(unsigned long start, unsigned long end)
{
void *page = __va(ALIGN_DOWN(start, PMD_SIZE));
vmemmap_flush_unused_pmd();
memset(__va(start), PAGE_UNUSED, end - start);
return !memchr_inv(page, PAGE_UNUSED, PMD_SIZE);
}