From: Will Deacon <will.deacon@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: aneesh.kumar@linux.vnet.ibm.com, akpm@linux-foundation.org,
npiggin@gmail.com, linux-arch@vger.kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux@armlinux.org.uk, heiko.carstens@de.ibm.com,
riel@surriel.com
Subject: Re: [PATCH v6 05/18] asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_mm()
Date: Tue, 19 Feb 2019 12:47:16 +0000 [thread overview]
Message-ID: <20190219124716.GB8501@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <20190219103233.148854086@infradead.org>
On Tue, Feb 19, 2019 at 11:31:53AM +0100, Peter Zijlstra wrote:
> When an architecture does not have (an efficient) flush_tlb_range(),
> but instead always uses full TLB invalidates, the current generic
> tlb_flush() is sub-optimal, for it will generate extra flushes in
> order to keep the range small.
>
> But if we cannot do range flushes, that is a moot concern. Optionally
> provide this simplified default.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> include/asm-generic/tlb.h | 41 ++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 40 insertions(+), 1 deletion(-)
>
> --- a/include/asm-generic/tlb.h
> +++ b/include/asm-generic/tlb.h
> @@ -114,7 +114,8 @@
> * returns the smallest TLB entry size unmapped in this range.
> *
> * If an architecture does not provide tlb_flush() a default implementation
> - * based on flush_tlb_range() will be used.
> + * based on flush_tlb_range() will be used, unless MMU_GATHER_NO_RANGE is
> + * specified, in which case we'll default to flush_tlb_mm().
> *
> * Additionally there are a few opt-in features:
> *
> @@ -140,6 +141,9 @@
> * the page-table pages. Required if you use HAVE_RCU_TABLE_FREE and your
> * architecture uses the Linux page-tables natively.
> *
> + * MMU_GATHER_NO_RANGE
> + *
> + * Use this if your architecture lacks an efficient flush_tlb_range().
> */
> #define HAVE_GENERIC_MMU_GATHER
>
> @@ -302,12 +306,45 @@ static inline void __tlb_reset_range(str
> */
> }
>
> +#ifdef CONFIG_MMU_GATHER_NO_RANGE
> +
> +#if defined(tlb_flush) || defined(tlb_start_vma) || defined(tlb_end_vma)
> +#error MMU_GATHER_NO_RANGE relies on default tlb_flush(), tlb_start_vma() and tlb_end_vma()
> +#endif
> +
> +/*
> + * When an architecture does not have efficient means of range flushing TLBs
> + * there is no point in doing intermediate flushes on tlb_end_vma() to keep the
> + * range small. We equally don't have to worry about page granularity or other
> + * things.
> + *
> + * All we need to do is issue a full flush for any !0 range.
> + */
> +static inline void tlb_flush(struct mmu_gather *tlb)
> +{
> + if (tlb->end)
> + flush_tlb_mm(tlb->mm);
> +}
I guess another way we could handle these architectures is by
unconditionally resetting tlb->fullmm to 1, but this works too.
Acked-by: Will Deacon <will.deacon@arm.com>
Will
next prev parent reply other threads:[~2019-02-19 12:47 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-19 10:31 [PATCH v6 00/18] generic mmu_gather patches Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 01/18] asm-generic/tlb: Provide a comment Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 02/18] asm-generic/tlb: Provide HAVE_MMU_GATHER_PAGE_SIZE Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 03/18] asm-generic/tlb: Provide generic VIPT cache flush Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 04/18] asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_range() Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 05/18] asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_mm() Peter Zijlstra
2019-02-19 12:47 ` Will Deacon [this message]
2019-02-19 10:31 ` [PATCH v6 06/18] asm-generic/tlb: Conditionally provide tlb_migrate_finish() Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-19 13:41 ` Peter Zijlstra
2019-02-20 14:47 ` Will Deacon
2019-02-20 15:02 ` Matthew Wilcox
2019-02-19 10:31 ` [PATCH v6 07/18] asm-generic/tlb: Invert HAVE_RCU_TABLE_INVALIDATE Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 08/18] arm/tlb: Convert to generic mmu_gather Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 09/18] ia64/tlb: Conver " Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-21 2:52 ` Souptick Joarder
2019-02-19 10:31 ` [PATCH v6 10/18] sh/tlb: Convert SH " Peter Zijlstra
2019-12-03 11:19 ` Geert Uytterhoeven
2019-12-04 10:47 ` Peter Zijlstra
2019-12-04 12:32 ` Geert Uytterhoeven
2019-12-04 13:22 ` Guenter Roeck
2019-12-04 15:17 ` Geert Uytterhoeven
2019-12-04 19:03 ` Guenter Roeck
2019-12-04 13:34 ` Peter Zijlstra
2019-12-04 15:07 ` Geert Uytterhoeven
2019-12-04 16:41 ` Peter Zijlstra
2019-12-05 15:26 ` Geert Uytterhoeven
2020-07-15 19:45 ` John Paul Adrian Glaubitz
2019-12-05 19:24 ` Rob Landley
2019-12-05 19:23 ` Rich Felker
2020-07-15 19:49 ` John Paul Adrian Glaubitz
2019-12-05 19:30 ` John Paul Adrian Glaubitz
2019-12-05 22:56 ` Guenter Roeck
2019-12-06 13:38 ` John Paul Adrian Glaubitz
2019-12-06 14:03 ` Guenter Roeck
2019-02-19 10:31 ` [PATCH v6 11/18] um/tlb: Convert " Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 12/18] arch/tlb: Clean up simple architectures Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 13/18] asm-generic/tlb: Introduce HAVE_MMU_GATHER_NO_GATHER Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-19 10:32 ` [PATCH v6 14/18] s390/tlb: convert to generic mmu_gather Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-19 10:32 ` [PATCH v6 15/18] asm-generic/tlb: Remove arch_tlb*_mmu() Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 16/18] asm-generic/tlb: Remove HAVE_GENERIC_MMU_GATHER Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 17/18] asm-generic/tlb: Remove tlb_flush_mmu_free() Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 18/18] asm-generic/tlb: Remove tlb_table_flush() Peter Zijlstra
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190219124716.GB8501@fuggles.cambridge.arm.com \
--to=will.deacon@arm.com \
--cc=akpm@linux-foundation.org \
--cc=aneesh.kumar@linux.vnet.ibm.com \
--cc=heiko.carstens@de.ibm.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux@armlinux.org.uk \
--cc=npiggin@gmail.com \
--cc=peterz@infradead.org \
--cc=riel@surriel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).