d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

For not offpage zones the slab is placed at the end of page. Keg's uk_pgoff

Browse Source 
is calculated to guarantee that struct uma_slab is placed at pointer size
alignment. Calculation of real struct uma_slab size is done in keg_ctor()
and yet again in keg_large_init(), to check if we need an extra page. This
calculation can actually be performed at compile time.

- Add SIZEOF_UMA_SLAB macro to calculate size of struct uma_slab placed at
  an end of a page with alignment requirement.
- Use SIZEOF_UMA_SLAB in keg_ctor() and in keg_large_init(). This is a not
  a functional change.
- Use SIZEOF_UMA_SLAB in UMA_SLAB_SPACE definition and in keg_small_init().
  This is a potential bugfix, but in reality I don't think there are any
  systems affected, since compiler aligns struct uma_slab anyway.
This commit is contained in:
Gleb Smirnoff 2018-11-28 19:17:27 +00:00
parent b92c2c907e
commit 3d5e3df73f
2 changed files with 29 additions and 40 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

57
sys/vm/uma_core.c
View File

@ -1453,7 +1453,7 @@ keg_small_init(uma_keg_t keg)
if (keg->uk_flags & UMA_ZONE_OFFPAGE) if (keg->uk_flags & UMA_ZONE_OFFPAGE)
shsize = 0; shsize = 0;
else else
shsize = sizeof(struct uma_slab); shsize = SIZEOF_UMA_SLAB;
if (rsize <= slabsize - shsize) if (rsize <= slabsize - shsize)
keg->uk_ipers = (slabsize - shsize) / rsize; keg->uk_ipers = (slabsize - shsize) / rsize;
@ -1523,7 +1523,6 @@ keg_small_init(uma_keg_t keg)
static void static void
keg_large_init(uma_keg_t keg) keg_large_init(uma_keg_t keg)
{ {
u_int shsize;
KASSERT(keg != NULL, ("Keg is null in keg_large_init")); KASSERT(keg != NULL, ("Keg is null in keg_large_init"));
KASSERT((keg->uk_flags & UMA_ZFLAG_CACHEONLY) == 0, KASSERT((keg->uk_flags & UMA_ZFLAG_CACHEONLY) == 0,
@ -1536,23 +1535,17 @@ keg_large_init(uma_keg_t keg)
keg->uk_rsize = keg->uk_size; keg->uk_rsize = keg->uk_size;
/* Check whether we have enough space to not do OFFPAGE. */ /* Check whether we have enough space to not do OFFPAGE. */
if ((keg->uk_flags & UMA_ZONE_OFFPAGE) == 0) { if ((keg->uk_flags & UMA_ZONE_OFFPAGE) == 0 &&
shsize = sizeof(struct uma_slab); PAGE_SIZE * keg->uk_ppera - keg->uk_rsize < SIZEOF_UMA_SLAB) {
if (shsize & UMA_ALIGN_PTR) /*
shsize = (shsize & ~UMA_ALIGN_PTR) + * We can't do OFFPAGE if we're internal, in which case
(UMA_ALIGN_PTR + 1); * we need an extra page per allocation to contain the
* slab header.
if (PAGE_SIZE * keg->uk_ppera - keg->uk_rsize < shsize) { */
/* if ((keg->uk_flags & UMA_ZFLAG_INTERNAL) == 0)
* We can't do OFFPAGE if we're internal, in which case keg->uk_flags |= UMA_ZONE_OFFPAGE;
* we need an extra page per allocation to contain the else
* slab header. keg->uk_ppera++;
*/
if ((keg->uk_flags & UMA_ZFLAG_INTERNAL) == 0)
keg->uk_flags |= UMA_ZONE_OFFPAGE;
else
keg->uk_ppera++;
}
} }
if ((keg->uk_flags & UMA_ZONE_OFFPAGE) && if ((keg->uk_flags & UMA_ZONE_OFFPAGE) &&
@ -1693,20 +1686,11 @@ keg_ctor(void *mem, int size, void *udata, int flags)
/* /*
* If we're putting the slab header in the actual page we need to * If we're putting the slab header in the actual page we need to
* figure out where in each page it goes. This calculates a right * figure out where in each page it goes. See SIZEOF_UMA_SLAB
* justified offset into the memory on an ALIGN_PTR boundary. * macro definition.
*/ */
if (!(keg->uk_flags & UMA_ZONE_OFFPAGE)) { if (!(keg->uk_flags & UMA_ZONE_OFFPAGE)) {
u_int totsize; keg->uk_pgoff = (PAGE_SIZE * keg->uk_ppera) - SIZEOF_UMA_SLAB;
/* Size of the slab struct and free list */
totsize = sizeof(struct uma_slab);
if (totsize & UMA_ALIGN_PTR)
totsize = (totsize & ~UMA_ALIGN_PTR) +
(UMA_ALIGN_PTR + 1);
keg->uk_pgoff = (PAGE_SIZE * keg->uk_ppera) - totsize;
/* /*
* The only way the following is possible is if with our * The only way the following is possible is if with our
* UMA_ALIGN_PTR adjustments we are now bigger than * UMA_ALIGN_PTR adjustments we are now bigger than
@ -1714,13 +1698,10 @@ keg_ctor(void *mem, int size, void *udata, int flags)
* mathematically possible for all cases, so we make * mathematically possible for all cases, so we make
* sure here anyway. * sure here anyway.
*/ */
totsize = keg->uk_pgoff + sizeof(struct uma_slab); KASSERT(keg->uk_pgoff + sizeof(struct uma_slab) <=
if (totsize > PAGE_SIZE * keg->uk_ppera) { PAGE_SIZE * keg->uk_ppera,
printf("zone %s ipers %d rsize %d size %d\n", ("zone %s ipers %d rsize %d size %d slab won't fit",
zone->uz_name, keg->uk_ipers, keg->uk_rsize, zone->uz_name, keg->uk_ipers, keg->uk_rsize, keg->uk_size));
keg->uk_size);
panic("UMA slab won't fit.");
}
} }
if (keg->uk_flags & UMA_ZONE_HASH) if (keg->uk_flags & UMA_ZONE_HASH)

12
sys/vm/uma_int.h
View File

@ -139,9 +139,17 @@
#define UMA_MAX_WASTE 10 #define UMA_MAX_WASTE 10
/* /*
* Size of memory in a not offpage slab available for actual items. * Actual size of uma_slab when it is placed at an end of a page
* with pointer sized alignment requirement.
*/ */
#define UMA_SLAB_SPACE (UMA_SLAB_SIZE - sizeof(struct uma_slab)) #define SIZEOF_UMA_SLAB ((sizeof(struct uma_slab) & UMA_ALIGN_PTR) ? \
(sizeof(struct uma_slab) & ~UMA_ALIGN_PTR) + \
(UMA_ALIGN_PTR + 1) : sizeof(struct uma_slab))
/*
* Size of memory in a not offpage single page slab available for actual items.
*/
#define UMA_SLAB_SPACE (PAGE_SIZE - SIZEOF_UMA_SLAB)
/* /*
* I doubt there will be many cases where this is exceeded. This is the initial * I doubt there will be many cases where this is exceeded. This is the initial