Re: CVS commit: src/sys/external/bsd/drm/dist/bsd-core

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

lars%heidieker.de@localhost said:
> you can change the amount of memory allocated to the kmem_arena in
> uvm_km.c currently it's 2/3 of kva-space, probably it needs to be a
> bit lower on kva limited machines.

Thanks - I've just changed the "2/3" to "2/4", and now
my X server works again with DRI. This certainly needs
some good heuristics to get the right balance.
As said elsewhere, I'd prefer to give malloc(9) its old
alignment semantics back. There might be more code out there
which relies on it. Here is my patch. This can be somewhat
wasteful for allocation sizes which are just a little bit
larger than a multiple of the page size. For exact
multiples, it should be not different from the existing
code because a page is wasted for bookkeeping anyway.

best regards
Matthias


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# HG changeset patch
# Parent b72467925a50848b94d77e1963b1a08b4801ae44

diff -r b72467925a50 sys/kern/kern_malloc.c
--- a/sys/kern/kern_malloc.c    Tue Jan 31 13:28:26 2012 +0100
+++ b/sys/kern/kern_malloc.c    Tue Jan 31 18:34:17 2012 +0100
@@ -108,10 +108,13 @@
 #endif /* MALLOCLOG */
 {
        const int kmflags = (flags & M_NOWAIT) ? KM_NOSLEEP : KM_SLEEP;
-       const size_t allocsize = sizeof(struct malloc_header) + size;
+       size_t allocsize = sizeof(struct malloc_header) + size;
        struct malloc_header *mh;
        void *p;
 
+       if (size >= NBPG)
+               allocsize = size + NBPG;
+
        p = kmem_intr_alloc(allocsize, kmflags);
        if (p == NULL)
                return NULL;
@@ -119,6 +122,10 @@
        if ((flags & M_ZERO) != 0) {
                memset(p, 0, allocsize);
        }
+       if (size >= NBPG) {
+               p = (char *)p + NBPG - sizeof(*mh);
+               allocsize = size + sizeof(*mh);
+       }
        mh = (void *)p;
        mh->mh_size = allocsize;
 
@@ -137,11 +144,20 @@
 #endif /* MALLOCLOG */
 {
        struct malloc_header *mh;
+       size_t allocsize;
 
        mh = addr;
        mh--;
 
-       kmem_intr_free(mh, mh->mh_size);
+       if (mh->mh_size >= NBPG + sizeof(*mh)) {
+               addr = (char *)addr - NBPG;
+               allocsize = mh->mh_size + NBPG - sizeof(*mh);
+       } else {
+               addr = mh;
+               allocsize = mh->mh_size;
+       }
+               
+       kmem_intr_free(addr, allocsize);
 }
 
 /*