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authorDave Hansen <dave@sr71.net>2015-07-17 12:28:11 +0200
committerIngo Molnar <mingo@kernel.org>2015-07-18 03:42:35 +0200
commit0c8c0f03e3a292e031596484275c14cf39c0ab7a (patch)
treec1d012c83722e9fa3b7bc152e64697828f6cbc35 /kernel/fork.c
parenta97439aa1aec10387797b4abae3cf117de1c90d7 (diff)
downloadlinux-sh-0c8c0f03e3a292e031596484275c14cf39c0ab7a.tar.gz
x86/fpu, sched: Dynamically allocate 'struct fpu'
The FPU rewrite removed the dynamic allocations of 'struct fpu'. But, this potentially wastes massive amounts of memory (2k per task on systems that do not have AVX-512 for instance). Instead of having a separate slab, this patch just appends the space that we need to the 'task_struct' which we dynamically allocate already. This saves from doing an extra slab allocation at fork(). The only real downside here is that we have to stick everything and the end of the task_struct. But, I think the BUILD_BUG_ON()s I stuck in there should keep that from being too fragile. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1437128892-9831-2-git-send-email-mingo@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/fork.c')
-rw-r--r--kernel/fork.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 1bfefc6f96a4..431b67a6098c 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -287,15 +287,21 @@ static void set_max_threads(unsigned int max_threads_suggested)
max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
}
+int __weak arch_task_struct_size(void)
+{
+ return sizeof(struct task_struct);
+}
+
void __init fork_init(void)
{
+ int task_struct_size = arch_task_struct_size();
#ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
#ifndef ARCH_MIN_TASKALIGN
#define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
#endif
/* create a slab on which task_structs can be allocated */
task_struct_cachep =
- kmem_cache_create("task_struct", sizeof(struct task_struct),
+ kmem_cache_create("task_struct", task_struct_size,
ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
#endif