Remove (un)committed pages distinction
By: a guest | Jul 13th, 2010 | Syntax: Diff | Size: 13.52 KB | Hits: 124 | Expires: Never
- commit 9fac8d774138f03d80061c243400b67b48879fd5
- Author: Leandro Lucarella <llucax@gmail.com>
- Date: Sun Jan 17 18:29:52 2010 -0300
- Remove (un)committed pages distinction
- This distinction is only made by Windows, and adds an extra complexity
- that probably doesn't worth it (specially for other OSs, where this adds
- a little overhead too, in both space and time).
- Other OSs (like Linux) even do all the committing automatically, under the
- hood, see:
- http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;\
- f=Documentation/vm/overcommit-accounting;hb=HEAD
- diff --git a/gc/alloc.d b/gc/alloc.d
- index 575095b..eeebcf4 100644
- --- a/gc/alloc.d
- +++ b/gc/alloc.d
- @@ -92,24 +92,7 @@ version (D_Ddoc)
- void* os_mem_map(size_t nbytes);
- /**
- - * Commit memory.
- - * Returns:
- - * true success
- - * false failure
- - */
- - bool os_mem_commit(void* base, size_t offset, size_t nbytes);
- -
- - /**
- - * Decommit memory.
- - * Returns:
- - * true success
- - * false failure
- - */
- - bool os_mem_decommit(void* base, size_t offset, size_t nbytes);
- -
- - /**
- * Unmap memory allocated with os_mem_map().
- - * Memory must have already been decommitted.
- * Returns:
- * true success
- * false failure
- @@ -121,18 +104,8 @@ else static if (is(typeof(VirtualAlloc)))
- {
- void* os_mem_map(size_t nbytes)
- {
- - return VirtualAlloc(null, nbytes, MEM_RESERVE, PAGE_READWRITE);
- - }
- -
- - bool os_mem_commit(void* base, size_t offset, size_t nbytes)
- - {
- - void* p = VirtualAlloc(base + offset, nbytes, MEM_COMMIT, PAGE_READWRITE);
- - return p !is null;
- - }
- -
- - bool os_mem_decommit(void* base, size_t offset, size_t nbytes)
- - {
- - return VirtualFree(base + offset, nbytes, MEM_DECOMMIT) != 0;
- + return VirtualAlloc(null, nbytes, MEM_RESERVE | MEM_COMMIT,
- + PAGE_READWRITE);
- }
- bool os_mem_unmap(void* base, size_t nbytes)
- @@ -149,16 +122,6 @@ else static if (is(typeof(mmap)) && is(typeof(MAP_ANON)))
- return (p == MAP_FAILED) ? null : p;
- }
- - bool os_mem_commit(void* base, size_t offset, size_t nbytes)
- - {
- - return true;
- - }
- -
- - bool os_mem_decommit(void* base, size_t offset, size_t nbytes)
- - {
- - return true;
- - }
- -
- bool os_mem_unmap(void* base, size_t nbytes)
- {
- return munmap(base, nbytes) == 0;
- @@ -184,16 +147,6 @@ else static if (is(typeof(malloc)))
- return q;
- }
- - bool os_mem_commit(void* base, size_t offset, size_t nbytes)
- - {
- - return true;
- - }
- -
- - bool os_mem_decommit(void* base, size_t offset, size_t nbytes)
- - {
- - return true;
- - }
- -
- bool os_mem_unmap(void* base, size_t nbytes)
- {
- free(*cast(void**)(cast(byte*) base + nbytes));
- diff --git a/gc/gc.d b/gc/gc.d
- index 3dff4ea..9607d24 100644
- --- a/gc/gc.d
- +++ b/gc/gc.d
- @@ -645,13 +645,9 @@ class GC
- .memset(&pool.pagetable[pagenum + psz], B_PAGEPLUS, newsz - psz);
- return p;
- }
- - if (i == pool.ncommitted)
- + if (i == pool.npages)
- {
- - auto u = pool.extendPages(pagenum + newsz - pool.ncommitted);
- - if (u == OPFAIL)
- - break;
- - i = pagenum + newsz;
- - continue;
- + break;
- }
- if (pool.pagetable[i] != B_FREE)
- break;
- @@ -747,7 +743,7 @@ class GC
- for (sz = 0; sz < maxsz; sz++)
- {
- auto i = pagenum + psz + sz;
- - if (i == pool.ncommitted)
- + if (i == pool.npages)
- break;
- if (pool.pagetable[i] != B_FREE)
- { if (sz < minsz)
- @@ -755,17 +751,7 @@ class GC
- break;
- }
- }
- - if (sz >= minsz)
- - {
- - }
- - else if (pagenum + psz + sz == pool.ncommitted)
- - {
- - auto u = pool.extendPages(minsz - sz);
- - if (u == OPFAIL)
- - return 0;
- - sz = minsz;
- - }
- - else
- + if (sz < minsz)
- return 0;
- debug (MEMSTOMP) .memset(p + psize, 0xF0, (psz + sz) * PAGESIZE - psize);
- .memset(pool.pagetable + pagenum + psz, B_PAGEPLUS, sz);
- @@ -859,7 +845,7 @@ class GC
- // Free pages
- npages = 1;
- n = pagenum;
- - while (++n < pool.ncommitted && pool.pagetable[n] == B_PAGEPLUS)
- + while (++n < pool.npages && pool.pagetable[n] == B_PAGEPLUS)
- npages++;
- debug (MEMSTOMP) .memset(p, 0xF2, npages * PAGESIZE);
- pool.freePages(pagenum, npages);
- @@ -1290,8 +1276,8 @@ class GC
- for (n = 0; n < gcx.npools; n++)
- { Pool *pool = gcx.pooltable[n];
- - psize += pool.ncommitted * PAGESIZE;
- - for (size_t j = 0; j < pool.ncommitted; j++)
- + psize += pool.npages * PAGESIZE;
- + for (size_t j = 0; j < pool.npages; j++)
- {
- Bins bin = cast(Bins)pool.pagetable[j];
- if (bin == B_FREE)
- @@ -1326,7 +1312,6 @@ class GC
- enum
- { PAGESIZE = 4096,
- - COMMITSIZE = (4096*16),
- POOLSIZE = (4096*256),
- }
- @@ -1344,7 +1329,6 @@ enum
- B_PAGE, // start of large alloc
- B_PAGEPLUS, // continuation of large alloc
- B_FREE, // free page
- - B_UNCOMMITTED, // memory not committed for this page
- B_MAX
- }
- @@ -1646,7 +1630,7 @@ struct Gcx
- }
- else
- {
- - // we are in a B_FREE or B_UNCOMMITTED page
- + // we are in a B_FREE page
- return null;
- }
- }
- @@ -1673,12 +1657,12 @@ struct Gcx
- bin = cast(Bins)pool.pagetable[pagenum];
- size = binsize[bin];
- if (bin == B_PAGE)
- - { size_t npages = pool.ncommitted;
- + {
- ubyte* pt;
- size_t i;
- pt = &pool.pagetable[0];
- - for (i = pagenum + 1; i < npages; i++)
- + for (i = pagenum + 1; i < pool.npages; i++)
- {
- if (pt[i] != B_PAGEPLUS)
- break;
- @@ -1731,12 +1715,12 @@ struct Gcx
- info.size = binsize[bin];
- if (bin == B_PAGE)
- - { size_t npages = pool.ncommitted;
- + {
- ubyte* pt;
- size_t i;
- pt = &pool.pagetable[0];
- - for (i = pn + 1; i < npages; i++)
- + for (i = pn + 1; i < pool.npages; i++)
- {
- if (pt[i] != B_PAGEPLUS)
- break;
- @@ -1811,9 +1795,9 @@ struct Gcx
- size_t npages = (size + PAGESIZE - 1) / PAGESIZE;
- Pool* pool = newPool(npages);
- - if (!pool || pool.extendPages(npages) == OPFAIL)
- + if (!pool)
- return 0;
- - return pool.ncommitted * PAGESIZE;
- + return pool.npages * PAGESIZE;
- }
- @@ -1825,18 +1809,16 @@ struct Gcx
- size_t n;
- size_t pn;
- Pool* pool;
- - size_t ncommitted;
- for (n = 0; n < npools; n++)
- {
- pool = pooltable[n];
- - ncommitted = pool.ncommitted;
- - for (pn = 0; pn < ncommitted; pn++)
- + for (pn = 0; pn < pool.npages; pn++)
- {
- if (cast(Bins)pool.pagetable[pn] != B_FREE)
- break;
- }
- - if (pn < ncommitted)
- + if (pn < pool.npages)
- {
- n++;
- continue;
- @@ -1952,9 +1934,6 @@ struct Gcx
- //debug(PRINTF) printf("************Gcx::newPool(npages = %d)****************\n", npages);
- - // Round up to COMMITSIZE pages
- - npages = (npages + (COMMITSIZE/PAGESIZE) - 1) & ~(COMMITSIZE/PAGESIZE - 1);
- -
- // Minimum of POOLSIZE
- if (npages < POOLSIZE/PAGESIZE)
- npages = POOLSIZE/PAGESIZE;
- @@ -2101,7 +2080,7 @@ struct Gcx
- }
- else
- {
- - // Don't mark bits in B_FREE or B_UNCOMMITTED pages
- + // Don't mark bits in B_FREE pages
- continue;
- }
- @@ -2345,7 +2324,7 @@ struct Gcx
- pn--;
- }
- u = 1;
- - while (pn + u < pool.ncommitted && pool.pagetable[pn + u] == B_PAGEPLUS)
- + while (pn + u < pool.npages && pool.pagetable[pn + u] == B_PAGEPLUS)
- u++;
- mark(o, o + u * PAGESIZE);
- }
- @@ -2362,13 +2341,11 @@ struct Gcx
- size_t freed = 0;
- for (n = 0; n < npools; n++)
- { size_t pn;
- - size_t ncommitted;
- uint* bbase;
- pool = pooltable[n];
- bbase = pool.mark.base();
- - ncommitted = pool.ncommitted;
- - for (pn = 0; pn < ncommitted; pn++, bbase += PAGESIZE / (32 * 16))
- + for (pn = 0; pn < pool.npages; pn++, bbase += PAGESIZE / (32 * 16))
- {
- Bins bin = cast(Bins)pool.pagetable[pn];
- @@ -2445,7 +2422,7 @@ struct Gcx
- pool.pagetable[pn] = B_FREE;
- freedpages++;
- debug (MEMSTOMP) .memset(p, 0xF3, PAGESIZE);
- - while (pn + 1 < ncommitted && pool.pagetable[pn + 1] == B_PAGEPLUS)
- + while (pn + 1 < pool.npages && pool.pagetable[pn + 1] == B_PAGEPLUS)
- {
- pn++;
- pool.pagetable[pn] = B_FREE;
- @@ -2469,11 +2446,9 @@ struct Gcx
- size_t recoveredpages = 0;
- for (n = 0; n < npools; n++)
- { size_t pn;
- - size_t ncommitted;
- pool = pooltable[n];
- - ncommitted = pool.ncommitted;
- - for (pn = 0; pn < ncommitted; pn++)
- + for (pn = 0; pn < pool.npages; pn++)
- {
- Bins bin = cast(Bins)pool.pagetable[pn];
- size_t biti;
- @@ -2740,7 +2715,6 @@ struct Pool
- GCBits noscan; // entries that should not be scanned
- size_t npages;
- - size_t ncommitted; // ncommitted <= npages
- ubyte* pagetable;
- @@ -2775,10 +2749,9 @@ struct Pool
- pagetable = cast(ubyte*) .malloc(npages);
- if (!pagetable)
- onOutOfMemoryError();
- - .memset(pagetable, B_UNCOMMITTED, npages);
- + .memset(pagetable, B_FREE, npages);
- this.npages = npages;
- - ncommitted = 0;
- }
- @@ -2788,13 +2761,6 @@ struct Pool
- {
- int result;
- - if (ncommitted)
- - {
- - result = os_mem_decommit(baseAddr, 0, ncommitted * PAGESIZE);
- - assert(result);
- - ncommitted = 0;
- - }
- -
- if (npages)
- {
- result = os_mem_unmap(baseAddr, npages * PAGESIZE);
- @@ -2832,7 +2798,6 @@ struct Pool
- //if (baseAddr + npages * PAGESIZE != topAddr)
- //printf("baseAddr = %p, npages = %d, topAddr = %p\n", baseAddr, npages, topAddr);
- assert(baseAddr + npages * PAGESIZE == topAddr);
- - assert(ncommitted <= npages);
- }
- for (size_t i = 0; i < npages; i++)
- @@ -2854,7 +2819,7 @@ struct Pool
- //debug(PRINTF) printf("Pool::allocPages(n = %d)\n", n);
- n2 = n;
- - for (i = 0; i < ncommitted; i++)
- + for (i = 0; i < npages; i++)
- {
- if (pagetable[i] == B_FREE)
- {
- @@ -2866,39 +2831,6 @@ struct Pool
- else
- n2 = n;
- }
- - return extendPages(n);
- - }
- -
- - /**
- - * Extend Pool by n pages.
- - * Returns OPFAIL on failure.
- - */
- - size_t extendPages(size_t n)
- - {
- - //debug(PRINTF) printf("Pool::extendPages(n = %d)\n", n);
- - if (ncommitted + n <= npages)
- - {
- - size_t tocommit;
- -
- - tocommit = (n + (COMMITSIZE/PAGESIZE) - 1) & ~(COMMITSIZE/PAGESIZE - 1);
- - if (ncommitted + tocommit > npages)
- - tocommit = npages - ncommitted;
- - //debug(PRINTF) printf("\tlooking to commit %d more pages\n", tocommit);
- - //fflush(stdout);
- - if (os_mem_commit(baseAddr, ncommitted * PAGESIZE, tocommit * PAGESIZE))
- - {
- - .memset(pagetable + ncommitted, B_FREE, tocommit);
- - auto i = ncommitted;
- - ncommitted += tocommit;
- -
- - while (i && pagetable[i - 1] == B_FREE)
- - i--;
- -
- - return i;
- - }
- - //debug(PRINTF) printf("\tfailed to commit %d pages\n", tocommit);
- - }
- -
- return OPFAIL;
- }
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