lkml.org 
[lkml]   [2019]   [Dec]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 05/17] asm-generic/tlb: Rename HAVE_RCU_TABLE_NO_INVALIDATE
From
Date
On 12/16/19 7:10 PM, Aneesh Kumar K.V wrote:
> On 12/16/19 6:50 PM, Peter Zijlstra wrote:
>> On Mon, Dec 16, 2019 at 06:43:53PM +0530, Aneesh Kumar K.V wrote:
>>> On 12/16/19 6:07 PM, Peter Zijlstra wrote:
>>
>>>> I'm confused, are you saing you're happy to have PowerPC eat the extra
>>>> TLB invalidates? I thought you cared about PPC performance :-)
>>>>
>>>>
>>>
>>> Instead can we do
>>>
>>> static inline void tlb_table_invalidate(struct mmu_gather *tlb)
>>> {
>>> #ifndef CONFIG_MMU_GATHER_RCU_TABLE_FREE
>>>      * Invalidate page-table caches used by hardware walkers. Then we
>>> still
>>>      * need to RCU-sched wait while freeing the pages because software
>>>      * walkers can still be in-flight.
>>>      */
>>>     tlb_flush_mmu_tlbonly(tlb);
>>> #endif
>>> }
>>
>> How does that not break ARM/ARM64/s390 and x86 ?
>>
>
> Hmm I missed that usage of RCU_TABLE_NO_INVALIDATE.
>
> Ok I guess we need to revert this change that went upstream this merge
> window then
>
> commit 52162ec784fa05f3a4b1d8e84421279998be3773
> Author: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> Date:   Thu Oct 24 13:28:00 2019 +0530
>
>     powerpc/mm/book3s64/radix: Use freed_tables instead of need_flush_all
>
>
>
> I will review the change closely.


So __p*_free_tlb() routines on ppc64 just mark that we need a page walk
cache flush and the actual flush in done in tlb_flush_mmu. As per

d86564a2f085b79ec046a5cba90188e61235280 (mm/tlb, x86/mm: Support
invalidating TLB caches for RCU_TABLE_FREE ) that is not sufficient?

-aneesh

\
 
 \ /
  Last update: 2019-12-16 14:55    [W:0.055 / U:5.236 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site