From: Benjamin Herrenschmidt <benh@kernel•crashing.org>
To: "Aneesh Kumar K.V" <aneesh.kumar@linux•vnet.ibm.com>,
paulus@samba•org, mpe@ellerman•id.au
Cc: linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH 1/3] powerpc/mm/radix: Update pte update sequence for pte clear case
Date: Thu, 09 Feb 2017 14:49:48 +1100 [thread overview]
Message-ID: <1486612188.3401.14.camel@kernel.crashing.org> (raw)
In-Reply-To: <1486609101-5231-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
On Thu, 2017-02-09 at 08:28 +0530, Aneesh Kumar K.V wrote:
> In the kernel we do follow the below sequence in different code paths.
> pte = ptep_get_clear(ptep)
> ....
> set_pte_at(ptep, pte)
>
> We do that for mremap, autonuma protection update and softdirty clearing. This
> implies our optimization to skip a tlb flush when clearing a pte update is
> not valid, because for DD1 system that followup set_pte_at will be done witout
> doing the required tlbflush. Fix that by always doing the dd1 style pte update
> irrespective of new_pte value. In a later patch we will optimize the application
> exit case.
What about my change to set_pte_at() ? We seem to be overwriting valid PTEs,
shouldn't we deal with that ?
Cheers,
Ben.
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel•crashing.org>
> > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux•vnet.ibm.com>
> ---
> arch/powerpc/include/asm/book3s/64/radix.h | 12 +++---------
> 1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
> index b4d1302387a3..70a3cdcdbe47 100644
> --- a/arch/powerpc/include/asm/book3s/64/radix.h
> +++ b/arch/powerpc/include/asm/book3s/64/radix.h
> @@ -144,16 +144,10 @@ static inline unsigned long radix__pte_update(struct mm_struct *mm,
> > * new value of pte
> > */
> > new_pte = (old_pte | set) & ~clr;
> > - /*
> > - * If we are trying to clear the pte, we can skip
> > - * the below sequence and batch the tlb flush. The
> > - * tlb flush batching is done by mmu gather code
> > - */
> > - if (new_pte) {
> > - asm volatile("ptesync" : : : "memory");
> > - radix__flush_tlb_pte_p9_dd1(old_pte, mm, addr);
> > + asm volatile("ptesync" : : : "memory");
> > + radix__flush_tlb_pte_p9_dd1(old_pte, mm, addr);
> > + if (new_pte)
> > __radix_pte_update(ptep, 0, new_pte);
> > - }
> > } else
> > old_pte = __radix_pte_update(ptep, clr, set);
> > asm volatile("ptesync" : : : "memory");
next prev parent reply other threads:[~2017-02-09 3:50 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-09 2:58 [PATCH 1/3] powerpc/mm/radix: Update pte update sequence for pte clear case Aneesh Kumar K.V
2017-02-09 2:58 ` [PATCH 2/3] powerpc/mm/radix: Use ptep_get_and_clear_full when clearing pte for full mm Aneesh Kumar K.V
2017-02-14 4:17 ` Michael Neuling
2017-02-09 2:58 ` [PATCH 3/3] powerpc/mm/radix: Skip ptesync in pte update helpers Aneesh Kumar K.V
2017-02-14 4:17 ` Michael Neuling
2017-02-09 3:49 ` Benjamin Herrenschmidt [this message]
2017-02-09 4:15 ` [PATCH 1/3] powerpc/mm/radix: Update pte update sequence for pte clear case Benjamin Herrenschmidt
2017-02-09 4:34 ` Aneesh Kumar K.V
2017-02-14 4:17 ` Michael Neuling
2017-02-16 5:59 ` [1/3] " Michael Ellerman
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=1486612188.3401.14.camel@kernel.crashing.org \
--to=benh@kernel$(echo .)crashing.org \
--cc=aneesh.kumar@linux$(echo .)vnet.ibm.com \
--cc=linuxppc-dev@lists$(echo .)ozlabs.org \
--cc=mpe@ellerman$(echo .)id.au \
--cc=paulus@samba$(echo .)org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
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