From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Christoph Hellwig <hch@lst.de>,
Uladzislau Rezki <urezki@gmail.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Baoquan He <bhe@redhat.com>, John Ogness <jogness@linutronix.de>,
linux-arm-kernel@lists.infradead.org,
Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <maz@kernel.org>,
x86@kernel.org
Subject: Re: Excessive TLB flush ranges
Date: Tue, 16 May 2023 09:48:30 +0100 [thread overview]
Message-ID: <ZGNDXm54ieAOp77T@shell.armlinux.org.uk> (raw)
In-Reply-To: <87cz308y3s.ffs@tglx>
On Tue, May 16, 2023 at 10:44:07AM +0200, Thomas Gleixner wrote:
> On Tue, May 16 2023 at 09:19, Russell King wrote:
> > On Tue, May 16, 2023 at 08:37:18AM +0200, Thomas Gleixner wrote:
> >> void flush_tlb_kernel_vas(struct list_head *list, unsigned int num_entries):
> >>
> >> So that an architecture can decide whether it's worth to do walk the
> >> entries or whether it resorts to a flush all.
> >
> > Is "num_entries" what an arch would want to use? How would it use that?
> > It doesn't tell an arch whether there is a large range of many list
> > entries, or a single entry covering a large range.
>
> Does it matter?
>
> The total number of entries to flush is what accumulates and at some
> architecture specific threshold that becomes more expensive than a full
> flush, independent of the range of the individual list entries, no?
It depends what you mean by "num_entries" - is that the number of
pages to be flushed in total in the range?
If so, what does a valid "start" and "end" range passed to
__purge_vmap_area_lazy() mean for num_entries - does that go to
(end - start) / PAGE_SIZE, or would it still be restricted to the
sum of that per list entry? If so, what's the point of passing in
"start" and "end" to this function?
I'm not familiar with this code...
--
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next prev parent reply other threads:[~2023-05-16 8:49 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-15 16:43 Excessive TLB flush ranges Thomas Gleixner
2023-05-15 16:59 ` Russell King (Oracle)
2023-05-15 19:46 ` Thomas Gleixner
2023-05-15 21:11 ` Thomas Gleixner
2023-05-15 21:31 ` Russell King (Oracle)
2023-05-16 6:37 ` Thomas Gleixner
2023-05-16 6:46 ` Thomas Gleixner
2023-05-16 8:18 ` Thomas Gleixner
2023-05-16 8:20 ` Thomas Gleixner
2023-05-16 8:27 ` Russell King (Oracle)
2023-05-16 9:03 ` Thomas Gleixner
2023-05-16 10:05 ` Baoquan He
2023-05-16 14:21 ` Thomas Gleixner
2023-05-16 19:03 ` Thomas Gleixner
2023-05-17 9:38 ` Thomas Gleixner
2023-05-17 10:52 ` Baoquan He
2023-05-19 11:22 ` Thomas Gleixner
2023-05-19 11:49 ` Baoquan He
2023-05-19 14:13 ` Thomas Gleixner
2023-05-19 12:01 ` [RFC PATCH 1/3] mm/vmalloc.c: try to flush vmap_area one by one Baoquan He
2023-05-19 14:16 ` Thomas Gleixner
2023-05-19 12:02 ` [RFC PATCH 2/3] mm/vmalloc.c: Only flush VM_FLUSH_RESET_PERMS area immediately Baoquan He
2023-05-19 12:03 ` [RFC PATCH 3/3] mm/vmalloc.c: change _vm_unmap_aliases() to do purge firstly Baoquan He
2023-05-19 14:17 ` Thomas Gleixner
2023-05-19 18:38 ` Thomas Gleixner
2023-05-19 23:46 ` Baoquan He
2023-05-21 23:10 ` Thomas Gleixner
2023-05-22 11:21 ` Baoquan He
2023-05-22 12:02 ` Thomas Gleixner
2023-05-22 14:34 ` Baoquan He
2023-05-22 20:21 ` Thomas Gleixner
2023-05-22 20:44 ` Thomas Gleixner
2023-05-23 9:35 ` Baoquan He
2023-05-19 13:49 ` Excessive TLB flush ranges Thomas Gleixner
2023-05-16 8:21 ` Russell King (Oracle)
2023-05-16 8:19 ` Russell King (Oracle)
2023-05-16 8:44 ` Thomas Gleixner
2023-05-16 8:48 ` Russell King (Oracle) [this message]
2023-05-16 12:09 ` Thomas Gleixner
2023-05-16 13:42 ` Uladzislau Rezki
2023-05-16 14:38 ` Thomas Gleixner
2023-05-16 15:01 ` Uladzislau Rezki
2023-05-16 17:04 ` Thomas Gleixner
2023-05-17 11:26 ` Uladzislau Rezki
2023-05-17 11:58 ` Thomas Gleixner
2023-05-17 12:15 ` Uladzislau Rezki
2023-05-17 16:32 ` Thomas Gleixner
2023-05-19 10:01 ` Uladzislau Rezki
2023-05-19 14:56 ` Thomas Gleixner
2023-05-19 15:14 ` Uladzislau Rezki
2023-05-19 16:32 ` Thomas Gleixner
2023-05-19 17:02 ` Uladzislau Rezki
2023-05-16 17:56 ` Nadav Amit
2023-05-16 19:32 ` Thomas Gleixner
2023-05-17 0:23 ` Thomas Gleixner
2023-05-17 1:23 ` Nadav Amit
2023-05-17 10:31 ` Thomas Gleixner
2023-05-17 11:47 ` Thomas Gleixner
2023-05-17 22:41 ` Nadav Amit
2023-05-17 14:43 ` Mark Rutland
2023-05-17 16:41 ` Thomas Gleixner
2023-05-17 22:57 ` Nadav Amit
2023-05-19 11:49 ` Thomas Gleixner
2023-05-17 12:12 ` Russell King (Oracle)
2023-05-17 23:14 ` Nadav Amit
2023-05-15 18:17 ` Uladzislau Rezki
2023-05-16 2:26 ` Baoquan He
2023-05-16 6:40 ` Thomas Gleixner
2023-05-16 8:07 ` Baoquan He
2023-05-16 8:10 ` Baoquan He
2023-05-16 8:45 ` Russell King (Oracle)
2023-05-16 9:13 ` Thomas Gleixner
2023-05-16 8:54 ` Thomas Gleixner
2023-05-16 9:48 ` Baoquan He
2023-05-15 20:02 ` Nadav Amit
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