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From: ypodemsk@redhat.com
To: Nadav Amit <nadav.amit@gmail.com>
Cc: mtosatti@redhat.com, ppandit@redhat.com,
	David Hildenbrand <david@redhat.com>,
	"Russell King (Oracle)" <linux@armlinux.org.uk>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Nicholas Piggin <npiggin@gmail.com>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	Heiko Carstens <hca@linux.ibm.com>,
	gor@linux.ibm.com, agordeev@linux.ibm.com,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	svens@linux.ibm.com, "David S. Miller" <davem@davemloft.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Kees Cook <keescook@chromium.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	frederic@kernel.org, Will Deacon <will@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	ardb@kernel.org, samitolvanen@google.com,
	juerg.haefliger@canonical.com, Arnd Bergmann <arnd@arndb.de>,
	rmk+kernel@armlinux.org.uk, geert+renesas@glider.be,
	linus.walleij@linaro.org,
	Andrew Morton <akpm@linux-foundation.org>,
	sebastian.reichel@collabora.com, Mike Rapoport <rppt@kernel.org>,
	aneesh.kumar@linux.ibm.com,
	the arch/x86 maintainers <x86@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	linux-s390 <linux-s390@vger.kernel.org>,
	sparclinux@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-mm <linux-mm@kvack.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to MM CPUs
Date: Thu, 22 Jun 2023 16:57:39 +0300	[thread overview]
Message-ID: <c08d81286b9986c086e9b68e3440f9bf99086d70.camel@redhat.com> (raw)
In-Reply-To: <10050BB1-15A4-4E84-B900-B21500B2079B@gmail.com>

On Wed, 2023-06-21 at 11:02 -0700, Nadav Amit wrote:
> > On Jun 20, 2023, at 7:46 AM, Yair Podemsky <ypodemsk@redhat.com>
> > wrote:
> > 
> > @@ -1525,7 +1525,7 @@ static void collapse_and_free_pmd(struct
> > mm_struct *mm, struct vm_area_struct *v
> > 				addr + HPAGE_PMD_SIZE);
> > 	mmu_notifier_invalidate_range_start(&range);
> > 	pmd = pmdp_collapse_flush(vma, addr, pmdp);
> > -	tlb_remove_table_sync_one();
> > +	tlb_remove_table_sync_one(mm);
> 
> Can’t pmdp_collapse_flush() have one additional argument
> “freed_tables”
> that it would propagate, for instance on x86 to flush_tlb_mm_range()
> ?
> Then you would not need tlb_remove_table_sync_one() to issue an
> additional
> IPI, no?
> 
> It just seems that you might still have 2 IPIs in many cases instead
> of
> one, and unless I am missing something, I don’t see why.
> 
Hi Nadav,
Thanks for your comment.
I think you are right and in some configurations 2 IPIs might occur.
However I a am not really dealing with the thp code at the moment,
This patch is about the mmu_gatherer and mostly dealing with IPIs sent
via the other code path.
Thanks,
Yair


  reply	other threads:[~2023-06-22 13:58 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-20 14:46 [PATCH v2 0/2] send tlb_remove_table_smp_sync IPI only to necessary CPUs Yair Podemsky
2023-06-20 14:46 ` [PATCH v2 1/2] arch: Introduce ARCH_HAS_CPUMASK_BITS Yair Podemsky
2023-06-20 14:46 ` [PATCH v2 2/2] mm/mmu_gather: send tlb_remove_table_smp_sync IPI only to MM CPUs Yair Podemsky
2023-06-21 17:42   ` Dave Hansen
2023-06-22 13:14     ` ypodemsk
2023-06-22 13:37       ` Dave Hansen
2023-06-26 14:36         ` ypodemsk
2023-06-26 15:23           ` Dave Hansen
2023-06-21 18:02   ` Nadav Amit
2023-06-22 13:57     ` ypodemsk [this message]
2023-06-23  3:38     ` Yang Shi
2023-07-03 13:57   ` Peter Zijlstra
2023-06-21  7:43 ` [PATCH v2 0/2] send tlb_remove_table_smp_sync IPI only to necessary CPUs Peter Zijlstra
2023-06-22 12:47   ` Marcelo Tosatti
2023-07-03 14:09     ` Peter Zijlstra
2023-06-22 13:11   ` ypodemsk

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