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From: Andrew Morton <akpm@linux-foundation.org>
To: Arjun Roy <arjunroy.kdev@gmail.com>
Cc: davem@davemloft.net, netdev@vger.kernel.org, linux-mm@kvack.org,
	arjunroy@google.com, Eric Dumazet <edumazet@google.com>,
	Soheil Hassas Yeganeh <soheil@google.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH resend mm,net-next 2/3] mm: Add vm_insert_pages().
Date: Wed, 12 Feb 2020 18:41:01 -0800	[thread overview]
Message-ID: <20200212184101.b8551710bd19c8216d62290d@linux-foundation.org> (raw)
In-Reply-To: <20200128025958.43490-2-arjunroy.kdev@gmail.com>

On Mon, 27 Jan 2020 18:59:57 -0800 Arjun Roy <arjunroy.kdev@gmail.com> wrote:

> Add the ability to insert multiple pages at once to a user VM with
> lower PTE spinlock operations.
> 
> The intention of this patch-set is to reduce atomic ops for
> tcp zerocopy receives, which normally hits the same spinlock multiple
> times consecutively.

Seems sensible, thanks.  Some other vm_insert_page() callers might want
to know about this, but I can't immediately spot any which appear to be
high bandwidth.

Is there much point in keeping the vm_insert_page() implementation
around?  Replace it with

static inline int
vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
	       struct page *page)
{
	return vm_insert_pages(vma, addr, &page, 1);
}

?

Also, vm_insert_page() does

	if (!page_count(page))
		return -EINVAL;

and this was not carried over into vm_insert_pages().  How come?

I don't know what that test does - it was added by Linus in the
original commit a145dd411eb28c83.  It's only been 15 years so I'm sure
he remembers ;)


  reply	other threads:[~2020-02-13  2:41 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-28  2:59 [PATCH resend mm,net-next 1/3] mm: Refactor insert_page to prepare for batched-lock insert Arjun Roy
2020-01-28  2:59 ` [PATCH resend mm,net-next 2/3] mm: Add vm_insert_pages() Arjun Roy
2020-02-13  2:41   ` Andrew Morton [this message]
2020-02-13 17:09     ` Arjun Roy
2020-02-13 21:37     ` Linus Torvalds
2020-02-13 21:54   ` Matthew Wilcox
2020-02-13 22:06     ` Arjun Roy
2020-01-28  2:59 ` [PATCH resend mm,net-next 3/3] net-zerocopy: Use vm_insert_pages() for tcp rcv zerocopy Arjun Roy
2020-02-13  2:56   ` Andrew Morton
2020-02-17  2:49     ` Arjun Roy
2020-02-21 21:21       ` Arjun Roy
2020-02-24  3:37         ` Andrew Morton
2020-02-24 16:19           ` Arjun Roy
2020-04-10 19:04         ` Andrew Morton
2020-04-10 19:13           ` Arjun Roy
2020-04-10 19:15           ` Arjun Roy
2020-02-13  2:41 ` [PATCH resend mm,net-next 1/3] mm: Refactor insert_page to prepare for batched-lock insert Andrew Morton
2020-02-13 16:52   ` Arjun Roy
2020-02-13 16:55   ` Arjun Roy

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