On 04/13/2012 16:45, Konstantin Belousov wrote:
On Fri, Apr 13, 2012 at 11:37:44AM -0700, Sushanth Rai wrote:
I've attached the simple program that creates 5 threads. Following is the o/p of
/proc/<pid>/map when this program is running. Note that I modified
sys/fs/procfs/procfs_map.c to print whether a region is wired. As you can see
from this o/p, none of stack areas get wired.
0x400000 0x401000 1 0 0xffffff002d943bd0 r-x 1 0 0x1000 COW NC wired vnode
/var/tmp/thread1
0x500000 0x501000 1 0 0xffffff002dd13e58 rw- 2 0 0x3100 NCOW NNC wired default -
0x501000 0x600000 255 0 0xffffff002dd13e58 rwx 2 0 0x3100 NCOW NNC wired
default -
0x800500000 0x800526000 38 0 0xffffff0025574000 r-x 192 46 0x1004 COW NC wired
vnode /libexec/ld-elf.so.1
0x800526000 0x800537000 17 0 0xffffff002d9f81b0 rw- 1 0 0x3100 NCOW NNC wired
default -
0x800626000 0x80062d000 7 0 0xffffff002dd13bd0 rw- 1 0 0x3100 COW NNC wired
vnode /libexec/ld-elf.so.1
0x80062d000 0x800633000 6 0 0xffffff002dd145e8 rw- 1 0 0x3100 NCOW NNC wired
default -
0x800633000 0x800645000 18 0 0xffffff00256d71b0 r-x 63 42 0x4 COW NC wired
vnode /lib/libthr.so.3
0x800645000 0x800646000 1 0 0xffffff002d975510 r-x 1 0 0x3100 COW NNC wired
vnode /lib/libthr.so.3
0x800646000 0x800746000 0 0 0xffffff002dc5cca8 --- 4 0 0x3100 NCOW NNC
not-wired default -
0x800746000 0x80074a000 4 0 0xffffff002572a288 rw- 1 0 0x3100 COW NNC wired
vnode /lib/libthr.so.3
0x80074a000 0x80074c000 2 0 0xffffff002dc5cca8 rw- 4 0 0x3100 NCOW NNC wired
default -
0x80074c000 0x80083e000 242 0 0xffffff001cd226c0 r-x 238 92 0x1004 COW NC wired
vnode /lib/libc.so.7
0x80083e000 0x80083f000 1 0 0xffffff002dd12000 r-x 1 0 0x3100 COW NNC wired
vnode /lib/libc.so.7
0x80083f000 0x80093e000 0 0 0xffffff002dc5cca8 --- 4 0 0x3100 NCOW NNC
not-wired default -
0x80093e000 0x80095d000 31 0 0xffffff002dddc360 rw- 1 0 0x3100 COW NNC wired
vnode /lib/libc.so.7
0x80095d000 0x800974000 23 0 0xffffff002dc5cca8 rw- 4 0 0x3100 NCOW NNC wired
default -
0x800a00000 0x800b00000 256 0 0xffffff002dbd1798 rw- 1 0 0x3100 NCOW NNC wired
default -
0x800b00000 0x800c00000 256 0 0xffffff002dd14948 rw- 1 0 0x3100 NCOW NNC wired
default -
0x7fffff3db000 0x7fffff3fb000 1 0 0xffffff002dbb4360 rw- 1 0 0x3100 NCOW NNC
not-wired default -
0x7fffff5dc000 0x7fffff5fc000 1 0 0xffffff002dc66af8 rw- 1 0 0x3100 NCOW NNC
not-wired default -
0x7fffff7dd000 0x7fffff7fd000 1 0 0xffffff002dbea438 rw- 1 0 0x3100 NCOW NNC
not-wired default -
0x7fffff9de000 0x7fffff9fe000 1 0 0xffffff002dd7fd80 rw- 1 0 0x3100 NCOW NNC
not-wired default -
0x7fffffbdf000 0x7fffffbff000 1 0 0xffffff002dbe9438 rw- 1 0 0x3100 NCOW NNC
not-wired default -
0x7fffffbff000 0x7fffffc00000 0 0 0 --- 0 0 0x0 NCOW NNC not-wired none -
0x7ffffffe0000 0x800000000000 32 0 0xffffff002dd125e8 rwx 1 0 0x3100 NCOW NNC
wired default -
--- On Fri, 4/13/12, Konstantin Belousov<kostik...@gmail.com> wrote:
From: Konstantin Belousov<kostik...@gmail.com>
Subject: Re: mlockall() on freebsd 7.2 + amd64 returns EAGAIN
To: "Sushanth Rai"<sushanth_...@yahoo.com>
Cc: freebsd-hackers@freebsd.org
Date: Friday, April 13, 2012, 1:11 AM
On Thu, Apr 12, 2012 at 08:10:26PM
-0700, Sushanth Rai wrote:
Then it should be fixed in r190885.
Thanks. That works like a charm.
mlockall() mostly works now. There is still a, issue in
wiring the stacks of multithreaded program when the program
uses default stack allocation scheme. Thread library
allocates stack for each thread by calling mmap() and
sending address and size to be mapped. The kernel adjusts
the start address to sgrowsz in vm_map_stack() and
maps at the adjusted address. But the subsequent wiring is
done using the original address, which fails.
Oh, I see. The problem is the VM_MAP_WIRE_NOHOLES flag. Since we
map only the initial stack fragment even for the MCL_WIREFUTURE maps,
there is a hole in the stack region.
In fact, for MCL_WIREFUTURE, we probably should map the whole
stack at once, prefaulting all pages.
Below are two patches. The change for vm_mmap.c would fix your immediate
problem by allowing holes in wired region.
The change for vm_map.c prefaults the whole stack instead of the
initial fragment. The single-threaded programs still get a fault
on stack growth.
The vm_mmap.c change looks ok to me. Please commit it. I haven't yet
had a chance to think about the other change.
Alan
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 6198629..2fd18d1 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -3259,7 +3259,10 @@ vm_map_stack(vm_map_t map, vm_offset_t addrbos,
vm_size_t max_ssize,
addrbos + max_ssize< addrbos)
return (KERN_NO_SPACE);
- init_ssize = (max_ssize< sgrowsiz) ? max_ssize : sgrowsiz;
+ if (map->flags& MAP_WIREFUTURE)
+ init_ssize = max_ssize;
+ else
+ init_ssize = (max_ssize< sgrowsiz) ? max_ssize : sgrowsiz;
PROC_LOCK(curthread->td_proc);
vmemlim = lim_cur(curthread->td_proc, RLIMIT_VMEM);
diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index 2588c85..3fccd9e 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -1561,9 +1561,11 @@ vm_mmap(vm_map_t map, vm_offset_t *addr, vm_size_t size,
vm_prot_t prot,
* If the process has requested that all future mappings
* be wired, then heed this.
*/
- if (map->flags& MAP_WIREFUTURE)
+ if (map->flags& MAP_WIREFUTURE) {
vm_map_wire(map, *addr, *addr + size,
- VM_MAP_WIRE_USER | VM_MAP_WIRE_NOHOLES);
+ VM_MAP_WIRE_USER | ((flags& MAP_STACK) ?
+ VM_MAP_WIRE_HOLESOK : VM_MAP_WIRE_NOHOLES));
+ }
} else {
/*
* If this mapping was accounted for in the vnode's
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