From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org, Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>, Jason Gunthorpe <jgg@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-riscv@lists.infradead.org, x86@kernel.org
Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions
Date: Fri, 26 Apr 2024 09:17:47 +0200 [thread overview]
Message-ID: <e685c532-8330-4a57-bc08-c67845e0c352@redhat.com> (raw)
In-Reply-To: <20240402125516.223131-2-david@redhat.com>
On 02.04.24 14:55, David Hildenbrand wrote:
> Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename
> all relevant internal functions to start with "gup_fast", to make it
> clearer that this is not ordinary GUP. The current mixture of
> "lockless", "gup" and "gup_fast" is confusing.
>
> Further, avoid the term "huge" when talking about a "leaf" -- for
> example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the
> "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that
> stays.
>
> What remains is the "external" interface:
> * get_user_pages_fast_only()
> * get_user_pages_fast()
> * pin_user_pages_fast()
>
> The high-level internal functions for GUP-fast (+slow fallback) are now:
> * internal_get_user_pages_fast() -> gup_fast_fallback()
> * lockless_pages_from_mm() -> gup_fast()
>
> The basic GUP-fast walker functions:
> * gup_pgd_range() -> gup_fast_pgd_range()
> * gup_p4d_range() -> gup_fast_p4d_range()
> * gup_pud_range() -> gup_fast_pud_range()
> * gup_pmd_range() -> gup_fast_pmd_range()
> * gup_pte_range() -> gup_fast_pte_range()
> * gup_huge_pgd() -> gup_fast_pgd_leaf()
> * gup_huge_pud() -> gup_fast_pud_leaf()
> * gup_huge_pmd() -> gup_fast_pmd_leaf()
>
> The weird hugepd stuff:
> * gup_huge_pd() -> gup_fast_hugepd()
> * gup_hugepte() -> gup_fast_hugepte()
I just realized that we end up calling these from follow_hugepd() as
well. And something seems to be off, because gup_fast_hugepd() won't
have the VMA even in the slow-GUP case to pass it to gup_must_unshare().
So these are GUP-fast functions and the terminology seem correct. But
the usage from follow_hugepd() is questionable,
commit a12083d721d703f985f4403d6b333cc449f838f6
Author: Peter Xu <peterx@redhat.com>
Date: Wed Mar 27 11:23:31 2024 -0400
mm/gup: handle hugepd for follow_page()
states "With previous refactors on fast-gup gup_huge_pd(), most of the
code can be leveraged", which doesn't look quite true just staring the
the gup_must_unshare() call where we don't pass the VMA. Also,
"unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense
for slow GUP ...
@Peter, any insights?
--
Cheers,
David / dhildenb
WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org, Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>, Jason Gunthorpe <jgg@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-riscv@lists.infradead.org, x86@kernel.org
Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions
Date: Fri, 26 Apr 2024 09:17:47 +0200 [thread overview]
Message-ID: <e685c532-8330-4a57-bc08-c67845e0c352@redhat.com> (raw)
In-Reply-To: <20240402125516.223131-2-david@redhat.com>
On 02.04.24 14:55, David Hildenbrand wrote:
> Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename
> all relevant internal functions to start with "gup_fast", to make it
> clearer that this is not ordinary GUP. The current mixture of
> "lockless", "gup" and "gup_fast" is confusing.
>
> Further, avoid the term "huge" when talking about a "leaf" -- for
> example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the
> "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that
> stays.
>
> What remains is the "external" interface:
> * get_user_pages_fast_only()
> * get_user_pages_fast()
> * pin_user_pages_fast()
>
> The high-level internal functions for GUP-fast (+slow fallback) are now:
> * internal_get_user_pages_fast() -> gup_fast_fallback()
> * lockless_pages_from_mm() -> gup_fast()
>
> The basic GUP-fast walker functions:
> * gup_pgd_range() -> gup_fast_pgd_range()
> * gup_p4d_range() -> gup_fast_p4d_range()
> * gup_pud_range() -> gup_fast_pud_range()
> * gup_pmd_range() -> gup_fast_pmd_range()
> * gup_pte_range() -> gup_fast_pte_range()
> * gup_huge_pgd() -> gup_fast_pgd_leaf()
> * gup_huge_pud() -> gup_fast_pud_leaf()
> * gup_huge_pmd() -> gup_fast_pmd_leaf()
>
> The weird hugepd stuff:
> * gup_huge_pd() -> gup_fast_hugepd()
> * gup_hugepte() -> gup_fast_hugepte()
I just realized that we end up calling these from follow_hugepd() as
well. And something seems to be off, because gup_fast_hugepd() won't
have the VMA even in the slow-GUP case to pass it to gup_must_unshare().
So these are GUP-fast functions and the terminology seem correct. But
the usage from follow_hugepd() is questionable,
commit a12083d721d703f985f4403d6b333cc449f838f6
Author: Peter Xu <peterx@redhat.com>
Date: Wed Mar 27 11:23:31 2024 -0400
mm/gup: handle hugepd for follow_page()
states "With previous refactors on fast-gup gup_huge_pd(), most of the
code can be leveraged", which doesn't look quite true just staring the
the gup_must_unshare() call where we don't pass the VMA. Also,
"unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense
for slow GUP ...
@Peter, any insights?
--
Cheers,
David / dhildenb
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org, Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>, Jason Gunthorpe <jgg@nvidia.com>,
John Hubbard <jhubbard@nvidia.com>,
linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-riscv@lists.infradead.org, x86@kernel.org
Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions
Date: Fri, 26 Apr 2024 09:17:47 +0200 [thread overview]
Message-ID: <e685c532-8330-4a57-bc08-c67845e0c352@redhat.com> (raw)
In-Reply-To: <20240402125516.223131-2-david@redhat.com>
On 02.04.24 14:55, David Hildenbrand wrote:
> Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename
> all relevant internal functions to start with "gup_fast", to make it
> clearer that this is not ordinary GUP. The current mixture of
> "lockless", "gup" and "gup_fast" is confusing.
>
> Further, avoid the term "huge" when talking about a "leaf" -- for
> example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the
> "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that
> stays.
>
> What remains is the "external" interface:
> * get_user_pages_fast_only()
> * get_user_pages_fast()
> * pin_user_pages_fast()
>
> The high-level internal functions for GUP-fast (+slow fallback) are now:
> * internal_get_user_pages_fast() -> gup_fast_fallback()
> * lockless_pages_from_mm() -> gup_fast()
>
> The basic GUP-fast walker functions:
> * gup_pgd_range() -> gup_fast_pgd_range()
> * gup_p4d_range() -> gup_fast_p4d_range()
> * gup_pud_range() -> gup_fast_pud_range()
> * gup_pmd_range() -> gup_fast_pmd_range()
> * gup_pte_range() -> gup_fast_pte_range()
> * gup_huge_pgd() -> gup_fast_pgd_leaf()
> * gup_huge_pud() -> gup_fast_pud_leaf()
> * gup_huge_pmd() -> gup_fast_pmd_leaf()
>
> The weird hugepd stuff:
> * gup_huge_pd() -> gup_fast_hugepd()
> * gup_hugepte() -> gup_fast_hugepte()
I just realized that we end up calling these from follow_hugepd() as
well. And something seems to be off, because gup_fast_hugepd() won't
have the VMA even in the slow-GUP case to pass it to gup_must_unshare().
So these are GUP-fast functions and the terminology seem correct. But
the usage from follow_hugepd() is questionable,
commit a12083d721d703f985f4403d6b333cc449f838f6
Author: Peter Xu <peterx@redhat.com>
Date: Wed Mar 27 11:23:31 2024 -0400
mm/gup: handle hugepd for follow_page()
states "With previous refactors on fast-gup gup_huge_pd(), most of the
code can be leveraged", which doesn't look quite true just staring the
the gup_must_unshare() call where we don't pass the VMA. Also,
"unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense
for slow GUP ...
@Peter, any insights?
--
Cheers,
David / dhildenb
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org, Peter Xu <peterx@redhat.com>
Cc: linux-s390@vger.kernel.org, loongarch@lists.linux.dev,
linux-sh@vger.kernel.org, John Hubbard <jhubbard@nvidia.com>,
x86@kernel.org, linux-mips@vger.kernel.org,
linux-perf-users@vger.kernel.org, linux-mm@kvack.org,
Mike Rapoport <rppt@kernel.org>, Jason Gunthorpe <jgg@nvidia.com>,
linux-fsdevel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions
Date: Fri, 26 Apr 2024 09:17:47 +0200 [thread overview]
Message-ID: <e685c532-8330-4a57-bc08-c67845e0c352@redhat.com> (raw)
In-Reply-To: <20240402125516.223131-2-david@redhat.com>
On 02.04.24 14:55, David Hildenbrand wrote:
> Let's consistently call the "fast-only" part of GUP "GUP-fast" and rename
> all relevant internal functions to start with "gup_fast", to make it
> clearer that this is not ordinary GUP. The current mixture of
> "lockless", "gup" and "gup_fast" is confusing.
>
> Further, avoid the term "huge" when talking about a "leaf" -- for
> example, we nowadays check pmd_leaf() because pmd_huge() is gone. For the
> "hugepd"/"hugepte" stuff, it's part of the name ("is_hugepd"), so that
> stays.
>
> What remains is the "external" interface:
> * get_user_pages_fast_only()
> * get_user_pages_fast()
> * pin_user_pages_fast()
>
> The high-level internal functions for GUP-fast (+slow fallback) are now:
> * internal_get_user_pages_fast() -> gup_fast_fallback()
> * lockless_pages_from_mm() -> gup_fast()
>
> The basic GUP-fast walker functions:
> * gup_pgd_range() -> gup_fast_pgd_range()
> * gup_p4d_range() -> gup_fast_p4d_range()
> * gup_pud_range() -> gup_fast_pud_range()
> * gup_pmd_range() -> gup_fast_pmd_range()
> * gup_pte_range() -> gup_fast_pte_range()
> * gup_huge_pgd() -> gup_fast_pgd_leaf()
> * gup_huge_pud() -> gup_fast_pud_leaf()
> * gup_huge_pmd() -> gup_fast_pmd_leaf()
>
> The weird hugepd stuff:
> * gup_huge_pd() -> gup_fast_hugepd()
> * gup_hugepte() -> gup_fast_hugepte()
I just realized that we end up calling these from follow_hugepd() as
well. And something seems to be off, because gup_fast_hugepd() won't
have the VMA even in the slow-GUP case to pass it to gup_must_unshare().
So these are GUP-fast functions and the terminology seem correct. But
the usage from follow_hugepd() is questionable,
commit a12083d721d703f985f4403d6b333cc449f838f6
Author: Peter Xu <peterx@redhat.com>
Date: Wed Mar 27 11:23:31 2024 -0400
mm/gup: handle hugepd for follow_page()
states "With previous refactors on fast-gup gup_huge_pd(), most of the
code can be leveraged", which doesn't look quite true just staring the
the gup_must_unshare() call where we don't pass the VMA. Also,
"unlikely(pte_val(pte) != pte_val(ptep_get(ptep)" doesn't make any sense
for slow GUP ...
@Peter, any insights?
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2024-04-26 7:17 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-02 12:55 [PATCH v1 0/3] mm/gup: consistently call it GUP-fast David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` [PATCH v1 1/3] mm/gup: consistently name GUP-fast functions David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-13 20:07 ` John Hubbard
2024-04-13 20:07 ` John Hubbard
2024-04-13 20:07 ` John Hubbard
2024-04-13 20:07 ` John Hubbard
2024-04-26 7:17 ` David Hildenbrand [this message]
2024-04-26 7:17 ` David Hildenbrand
2024-04-26 7:17 ` David Hildenbrand
2024-04-26 7:17 ` David Hildenbrand
2024-04-26 13:44 ` Peter Xu
2024-04-26 13:44 ` Peter Xu
2024-04-26 13:44 ` Peter Xu
2024-04-26 13:44 ` Peter Xu
2024-04-26 16:12 ` Peter Xu
2024-04-26 16:12 ` Peter Xu
2024-04-26 16:12 ` Peter Xu
2024-04-26 16:12 ` Peter Xu
2024-04-26 17:28 ` David Hildenbrand
2024-04-26 17:28 ` David Hildenbrand
2024-04-26 17:28 ` David Hildenbrand
2024-04-26 17:28 ` David Hildenbrand
2024-04-26 21:20 ` Peter Xu
2024-04-26 21:20 ` Peter Xu
2024-04-26 21:20 ` Peter Xu
2024-04-26 21:20 ` Peter Xu
2024-04-26 21:33 ` David Hildenbrand
2024-04-26 21:33 ` David Hildenbrand
2024-04-26 21:33 ` David Hildenbrand
2024-04-26 21:33 ` David Hildenbrand
2024-04-26 21:58 ` Peter Xu
2024-04-26 21:58 ` Peter Xu
2024-04-26 21:58 ` Peter Xu
2024-04-26 21:58 ` Peter Xu
2024-04-27 6:58 ` David Hildenbrand
2024-04-27 6:58 ` David Hildenbrand
2024-04-27 6:58 ` David Hildenbrand
2024-04-27 6:58 ` David Hildenbrand
2024-04-02 12:55 ` [PATCH v1 2/3] mm/treewide: rename CONFIG_HAVE_FAST_GUP to CONFIG_HAVE_GUP_FAST David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 22:32 ` Jason Gunthorpe
2024-04-02 22:32 ` Jason Gunthorpe
2024-04-02 22:32 ` Jason Gunthorpe
2024-04-02 22:32 ` Jason Gunthorpe
2024-04-13 20:11 ` John Hubbard
2024-04-13 20:11 ` John Hubbard
2024-04-13 20:11 ` John Hubbard
2024-04-13 20:11 ` John Hubbard
2024-04-02 12:55 ` [PATCH v1 3/3] mm: use "GUP-fast" instead "fast GUP" in remaining comments David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 12:55 ` David Hildenbrand
2024-04-02 22:33 ` Jason Gunthorpe
2024-04-02 22:33 ` Jason Gunthorpe
2024-04-02 22:33 ` Jason Gunthorpe
2024-04-02 22:33 ` Jason Gunthorpe
2024-04-13 20:12 ` John Hubbard
2024-04-13 20:12 ` John Hubbard
2024-04-13 20:12 ` John Hubbard
2024-04-13 20:12 ` John Hubbard
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=e685c532-8330-4a57-bc08-c67845e0c352@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=jgg@nvidia.com \
--cc=jhubbard@nvidia.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-perf-users@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-sh@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=loongarch@lists.linux.dev \
--cc=peterx@redhat.com \
--cc=rppt@kernel.org \
--cc=x86@kernel.org \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.