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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 /include
parenta97439aa1aec10387797b4abae3cf117de1c90d7 (diff)
downloadlinux-0c8c0f03e3a292e031596484275c14cf39c0ab7a.tar.bz2
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 'include')
-rw-r--r--include/linux/sched.h12
1 files changed, 10 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index ae21f1591615..e43a41d892b6 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1522,8 +1522,6 @@ struct task_struct {
/* hung task detection */
unsigned long last_switch_count;
#endif
-/* CPU-specific state of this task */
- struct thread_struct thread;
/* filesystem information */
struct fs_struct *fs;
/* open file information */
@@ -1778,8 +1776,18 @@ struct task_struct {
unsigned long task_state_change;
#endif
int pagefault_disabled;
+/* CPU-specific state of this task */
+ struct thread_struct thread;
+/*
+ * WARNING: on x86, 'thread_struct' contains a variable-sized
+ * structure. It *MUST* be at the end of 'task_struct'.
+ *
+ * Do not put anything below here!
+ */
};
+extern int arch_task_struct_size(void);
+
/* Future-safe accessor for struct task_struct's cpus_allowed. */
#define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed)