On Tue, Oct 19, 2010 at 8:55 AM, Andriy Gapon <a...@freebsd.org> wrote:
> on 19/10/2010 00:01 Giovanni Trematerra said the following:
>>
>> Your patch seems just a work around about initial slab size where the
>> keg is backed.
>
> Well, setting aside my confusion with the terminology - yes, the patch is just
> that, and precisely because I only tried to solve that particular problem.
>
>> Having dynamic slab sizes would allow to have the keg backed on a larger slab
>> without going OFFPAGE.
>
> I agree in principle.
> But without seeing code that implements that I can't guess if it would really
> be
> more efficient or more maintainable, i.e. more useful in general.
> Still a very good idea.
>
Here the patch that was in my mind.
The patch doesn't implement dynamic slab size just allow
to have a multipage slab to back uma_zone objects.
I'm going to work more on the topic "dynamic slab size" soon.
I tested the patch on qemu with -smp 32.
I'm looking for real hw to test the patch on.
here some interesting output:
qemulab# vmstat -z | more
ITEM SIZE LIMIT USED FREE REQ FAIL SLEEP
UMA Kegs: 208, 0, 149, 4, 149, 0, 0
UMA Zones: 4480, 0, 149, 0, 149, 0, 0
UMA Slabs: 568, 0, 836, 4, 1187, 0, 0
UMA RCntSlabs: 568, 0, 202, 1, 202, 0, 0
UMA Hash: 256, 0, 2, 13, 3, 0, 0
qemulab# sysctl kern | grep cpu
kern.ccpu: 0
<cpu count="32" mask="0xffffffff">0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
28, 29, 30, 31</cpu>
kern.smp.cpus: 32
kern.smp.maxcpus: 32
Any feedback will be appreciate.
--
Giovanni Trematerra
==============================================================
diff -r 36572cbc6817 sys/vm/uma_core.c
--- a/sys/vm/uma_core.c Tue Oct 05 04:49:04 2010 -0400
+++ b/sys/vm/uma_core.c Mon Nov 01 11:54:38 2010 -0400
@@ -930,27 +930,36 @@ startup_alloc(uma_zone_t zone, int bytes
{
uma_keg_t keg;
uma_slab_t tmps;
-
- keg = zone_first_keg(zone);
+ u_int16_t pages;
+
+ keg = zone_first_keg(zone);
+ pages = bytes / PAGE_SIZE;
+
+ /* Account for remainder */
+ if ((pages * PAGE_SIZE) < bytes)
+ pages++;
+ KASSERT(pages > 0, ("startup_alloc can't reserve 0 pages\n"));
/*
* Check our small startup cache to see if it has pages remaining.
*/
mtx_lock(&uma_boot_pages_mtx);
- if ((tmps = LIST_FIRST(&uma_boot_pages)) != NULL) {
- LIST_REMOVE(tmps, us_link);
+ do {
+ if ((tmps = LIST_FIRST(&uma_boot_pages)) != NULL)
+ LIST_REMOVE(tmps, us_link);
+ } while (--pages && tmps != NULL);
+ if (tmps != NULL) {
mtx_unlock(&uma_boot_pages_mtx);
*pflag = tmps->us_flags;
return (tmps->us_data);
- }
+ } else if (booted == 0)
+ panic("UMA: Increase vm.boot_pages");
mtx_unlock(&uma_boot_pages_mtx);
- if (booted == 0)
- panic("UMA: Increase vm.boot_pages");
/*
* Now that we've booted reset these users to their real allocator.
*/
#ifdef UMA_MD_SMALL_ALLOC
- keg->uk_allocf = uma_small_alloc;
+ keg->uk_allocf = (keg->uk_ppera > 1) ? page_alloc : uma_small_alloc;
#else
keg->uk_allocf = page_alloc;
#endif
@@ -1163,7 +1172,7 @@ keg_small_init(uma_keg_t keg)
static void
keg_large_init(uma_keg_t keg)
{
- int pages;
+ u_int16_t pages;
KASSERT(keg != NULL, ("Keg is null in keg_large_init"));
KASSERT((keg->uk_flags & UMA_ZFLAG_CACHEONLY) == 0,
@@ -1177,12 +1186,15 @@ keg_large_init(uma_keg_t keg)
keg->uk_ppera = pages;
keg->uk_ipers = 1;
+ keg->uk_rsize = keg->uk_size;
+
+ /* We can't do OFFPAGE if we're internal, bail out here. */
+ if (keg->uk_flags & UMA_ZFLAG_INTERNAL)
+ return;
keg->uk_flags |= UMA_ZONE_OFFPAGE;
if ((keg->uk_flags & UMA_ZONE_VTOSLAB) == 0)
keg->uk_flags |= UMA_ZONE_HASH;
-
- keg->uk_rsize = keg->uk_size;
}
static void
@@ -1301,7 +1313,8 @@ keg_ctor(void *mem, int size, void *udat
#endif
if (booted == 0)
keg->uk_allocf = startup_alloc;
- }
+ } else if (booted == 0 && (keg->uk_flags & UMA_ZFLAG_INTERNAL))
+ keg->uk_allocf = startup_alloc;
/*
* Initialize keg's lock (shared among zones).
@@ -1330,7 +1343,7 @@ keg_ctor(void *mem, int size, void *udat
if (totsize & UMA_ALIGN_PTR)
totsize = (totsize & ~UMA_ALIGN_PTR) +
(UMA_ALIGN_PTR + 1);
- keg->uk_pgoff = UMA_SLAB_SIZE - totsize;
+ keg->uk_pgoff = (UMA_SLAB_SIZE * keg->uk_ppera) - totsize;
if (keg->uk_flags & UMA_ZONE_REFCNT)
totsize = keg->uk_pgoff + sizeof(struct uma_slab_refcnt)
@@ -1346,7 +1359,7 @@ keg_ctor(void *mem, int size, void *udat
* mathematically possible for all cases, so we make
* sure here anyway.
*/
- if (totsize > UMA_SLAB_SIZE) {
+ if (totsize > UMA_SLAB_SIZE * keg->uk_ppera) {
printf("zone %s ipers %d rsize %d size %d\n",
zone->uz_name, keg->uk_ipers, keg->uk_rsize,
keg->uk_size);
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