[PATCH v2 8/9] x86/mm/tlb: Remove UV special case

Nadav Amit
2019-07-03T07:14:21Z

SGI UV support is outdated and not maintained, and it is not clear how
it performs relatively to non-UV. Remove the code to simplify the code.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
arch/x86/mm/tlb.c | 25 -------------------------
1 file changed, 25 deletions(-)

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index b47a71820f35..64afe1215495 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -689,31 +689,6 @@ void native_flush_tlb_multi(const struct cpumask *cpumask,
trace_tlb_flush(TLB_REMOTE_SEND_IPI,
(info->end - info->start) >> PAGE_SHIFT);

- if (is_uv_system()) {
- /*
- * This whole special case is confused. UV has a "Broadcast
- * Assist Unit", which seems to be a fancy way to send IPIs.
- * Back when x86 used an explicit TLB flush IPI, UV was
- * optimized to use its own mechanism. These days, x86 uses
- * smp_call_function_many(), but UV still uses a manual IPI,
- * and that IPI's action is out of date -- it does a manual
- * flush instead of calling flush_tlb_func_remote(). This
- * means that the percpu tlb_gen variables won't be updated
- * and we'll do pointless flushes on future context switches.
- *
- * Rather than hooking native_flush_tlb_multi() here, I think
- * that UV should be updated so that smp_call_function_many(),
- * etc, are optimal on UV.
- */
- flush_tlb_func_local(info);
-
- cpumask = uv_flush_tlb_others(cpumask, info);
- if (cpumask)
- smp_call_function_many(cpumask, flush_tlb_func_remote,
- (void *)info, 1);
- return;
- }
-
/*
* If no page tables were freed, we can skip sending IPIs to
* CPUs in lazy TLB mode. They will flush the CPU themselves
--
2.17.1