On Thu, 22 Mar 2018, Cy Schubert wrote:

It broke i386 too.

I believe I'm not able to reproduce this because it is a result of changes in kernel config. I can not reproduce it so I can't verify the fix. Since you can, would you mind committing? I see no problem with the diff below.

Thanks,
Jeff


Index: sys/vm/vm_reserv.c
===================================================================
--- sys/vm/vm_reserv.c  (revision 331399)
+++ sys/vm/vm_reserv.c  (working copy)
@@ -45,8 +45,6 @@

#include <sys/param.h>
#include <sys/kernel.h>
-#include <sys/counter.h>
-#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
@@ -55,6 +53,8 @@
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
+#include <sys/counter.h>
+#include <sys/ktr.h>
#include <sys/vmmeter.h>
#include <sys/smp.h>

This is because sys/i386/include/machine.h uses critical_enter() and
critical_exit() which are defined in sys/systm.h.

It built nicely on my amd64's though.

~cy

In message <alpine.BSF.2.21.1803221451420.2307@desktop>, Jeff Roberson
writes:
Thank you, working on it.  I had done a make universe before getting
review feedback.

Jeff

On Thu, 22 Mar 2018, Justin Hibbits wrote:

This broke gcc builds.

On Thu, Mar 22, 2018 at 2:21 PM, Jeff Roberson <j...@freebsd.org> wrote:
Author: jeff
Date: Thu Mar 22 19:21:11 2018
New Revision: 331369
URL: https://svnweb.freebsd.org/changeset/base/331369

Log:
  Lock reservations with a dedicated lock in each reservation.  Protect th
e
  vmd_free_count with atomics.

  This allows us to allocate and free from reservations without the free l
ock
  except where a superpage is allocated from the physical layer, which is
  roughly 1/512 of the operations on amd64.

  Use the counter api to eliminate cache conention on counters.

  Reviewed by:  markj
  Tested by:    pho
  Sponsored by: Netflix, Dell/EMC Isilon
  Differential Revision:        https://reviews.freebsd.org/D14707

Modified:
  head/sys/vm/vm_page.c
  head/sys/vm/vm_pagequeue.h
  head/sys/vm/vm_reserv.c
  head/sys/vm/vm_reserv.h

Modified: head/sys/vm/vm_page.c
==========================================================================
====
--- head/sys/vm/vm_page.c       Thu Mar 22 19:11:43 2018        (r331368)
+++ head/sys/vm/vm_page.c       Thu Mar 22 19:21:11 2018        (r331369)
@@ -177,7 +177,6 @@ static uma_zone_t fakepg_zone;
 static void vm_page_alloc_check(vm_page_t m);
 static void vm_page_clear_dirty_mask(vm_page_t m, vm_page_bits_t pagebits
);
 static void vm_page_enqueue(uint8_t queue, vm_page_t m);
-static void vm_page_free_phys(struct vm_domain *vmd, vm_page_t m);
 static void vm_page_init(void *dummy);
 static int vm_page_insert_after(vm_page_t m, vm_object_t object,
     vm_pindex_t pindex, vm_page_t mpred);
@@ -1677,10 +1676,10 @@ vm_page_alloc_after(vm_object_t object, vm_pindex_
t pi
  * for the request class and false otherwise.
  */
 int
-vm_domain_available(struct vm_domain *vmd, int req, int npages)
+vm_domain_allocate(struct vm_domain *vmd, int req, int npages)
 {
+       u_int limit, old, new;

-       vm_domain_free_assert_locked(vmd);
        req = req & VM_ALLOC_CLASS_MASK;

        /*
@@ -1688,15 +1687,34 @@ vm_domain_available(struct vm_domain *vmd, int req
, in
         */
        if (curproc == pageproc && req != VM_ALLOC_INTERRUPT)
                req = VM_ALLOC_SYSTEM;
+       if (req == VM_ALLOC_INTERRUPT)
+               limit = 0;
+       else if (req == VM_ALLOC_SYSTEM)
+               limit = vmd->vmd_interrupt_free_min;
+       else
+               limit = vmd->vmd_free_reserved;

-       if (vmd->vmd_free_count >= npages + vmd->vmd_free_reserved ||
-           (req == VM_ALLOC_SYSTEM &&
-           vmd->vmd_free_count >= npages + vmd->vmd_interrupt_free_min) |
|
-           (req == VM_ALLOC_INTERRUPT &&
-           vmd->vmd_free_count >= npages))
-               return (1);
+       /*
+        * Attempt to reserve the pages.  Fail if we're below the limit.
+        */
+       limit += npages;
+       old = vmd->vmd_free_count;
+       do {
+               if (old < limit)
+                       return (0);
+               new = old - npages;
+       } while (atomic_fcmpset_int(&vmd->vmd_free_count, &old, new) == 0)
;

-       return (0);
+       /* Wake the page daemon if we've crossed the threshold. */
+       if (vm_paging_needed(vmd, new) && !vm_paging_needed(vmd, old))
+               pagedaemon_wakeup(vmd->vmd_domain);
+
+       /* Only update bitsets on transitions. */
+       if ((old >= vmd->vmd_free_min && new < vmd->vmd_free_min) ||
+           (old >= vmd->vmd_free_severe && new < vmd->vmd_free_severe))
+               vm_domain_set(vmd);
+
+       return (1);
 }

 vm_page_t
@@ -1723,44 +1741,34 @@ vm_page_alloc_domain_after(vm_object_t object, vm_
pind
 again:
        m = NULL;
 #if VM_NRESERVLEVEL > 0
+       /*
+        * Can we allocate the page from a reservation?
+        */
        if (vm_object_reserv(object) &&
-           (m = vm_reserv_extend(req, object, pindex, domain, mpred))
-           != NULL) {
+           ((m = vm_reserv_extend(req, object, pindex, domain, mpred)) !=
 NULL ||
+           (m = vm_reserv_alloc_page(req, object, pindex, domain, mpred))
 != NULL)) {
                domain = vm_phys_domain(m);
                vmd = VM_DOMAIN(domain);
                goto found;
        }
 #endif
        vmd = VM_DOMAIN(domain);
-       vm_domain_free_lock(vmd);
-       if (vm_domain_available(vmd, req, 1)) {
+       if (vm_domain_allocate(vmd, req, 1)) {
                /*
-                * Can we allocate the page from a reservation?
+                * If not, allocate it from the free page queues.
                 */
+               vm_domain_free_lock(vmd);
+               m = vm_phys_alloc_pages(domain, object != NULL ?
+                   VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0);
+               vm_domain_free_unlock(vmd);
+               if (m == NULL) {
+                       vm_domain_freecnt_inc(vmd, 1);
 #if VM_NRESERVLEVEL > 0
-               if (!vm_object_reserv(object) ||
-                   (m = vm_reserv_alloc_page(object, pindex,
-                   domain, mpred)) == NULL)
+                       if (vm_reserv_reclaim_inactive(domain))
+                               goto again;
 #endif
-               {
-                       /*
-                        * If not, allocate it from the free page queues.
-                        */
-                       m = vm_phys_alloc_pages(domain, object != NULL ?
-                           VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRECT, 0);
-#if VM_NRESERVLEVEL > 0
-                       if (m == NULL && vm_reserv_reclaim_inactive(domain
)) {
-                               m = vm_phys_alloc_pages(domain,
-                                   object != NULL ?
-                                   VM_FREEPOOL_DEFAULT : VM_FREEPOOL_DIRE
CT,
-                                   0);
-                       }
-#endif
                }
        }
-       if (m != NULL)
-               vm_domain_freecnt_dec(vmd, 1);
-       vm_domain_free_unlock(vmd);
        if (m == NULL) {
                /*
                 * Not allocatable, give up.
@@ -1775,9 +1783,7 @@ again:
         */
        KASSERT(m != NULL, ("missing page"));

-#if VM_NRESERVLEVEL > 0
 found:
-#endif

'found' is now declared, but unused on powerpc64.

- Justin



--
Cheers,
Cy Schubert <cy.schub...@cschubert.com>
FreeBSD UNIX:  <c...@freebsd.org>   Web:  http://www.FreeBSD.org

        The need of the many outweighs the greed of the few.


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