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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 /fs
parenta97439aa1aec10387797b4abae3cf117de1c90d7 (diff)
downloadlwn-0c8c0f03e3a292e031596484275c14cf39c0ab7a.tar.gz
lwn-0c8c0f03e3a292e031596484275c14cf39c0ab7a.zip
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 'fs')
-rw-r--r--fs/proc/kcore.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index 91a4e6426321..a0fe99485687 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -92,7 +92,7 @@ static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
roundup(sizeof(CORE_STR), 4)) +
roundup(sizeof(struct elf_prstatus), 4) +
roundup(sizeof(struct elf_prpsinfo), 4) +
- roundup(sizeof(struct task_struct), 4);
+ roundup(arch_task_struct_size(), 4);
*elf_buflen = PAGE_ALIGN(*elf_buflen);
return size + *elf_buflen;
}
@@ -415,7 +415,7 @@ static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
/* set up the task structure */
notes[2].name = CORE_STR;
notes[2].type = NT_TASKSTRUCT;
- notes[2].datasz = sizeof(struct task_struct);
+ notes[2].datasz = arch_task_struct_size();
notes[2].data = current;
nhdr->p_filesz += notesize(&notes[2]);