linux-kernel - Re: [PATCH v2 0/8] binder: faster page installations

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Message-ID: <CAJuCfpHmwwOXMfuM3K32U+KedUYiZBXC_rbTG288gPy1kQs46A@mail.gmail.com>
Date: Thu, 7 Nov 2024 08:18:53 -0800
From: Suren Baghdasaryan <surenb@...gle.com>
To: Carlos Llamas <cmllamas@...gle.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, linux-kernel@...r.kernel.org, 
	kernel-team@...roid.com, Alice Ryhl <aliceryhl@...gle.com>, 
	David Hildenbrand <david@...hat.com>, "Liam R. Howlett" <Liam.Howlett@...cle.com>, 
	Matthew Wilcox <willy@...radead.org>, Minchan Kim <minchan@...nel.org>, Nhat Pham <nphamcs@...il.com>, 
	Johannes Weiner <hannes@...xchg.org>, Todd Kjos <tkjos@...gle.com>, 
	Viktor Martensson <vmartensson@...gle.com>, Hillf Danton <hdanton@...a.com>, 
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Subject: Re: [PATCH v2 0/8] binder: faster page installations

On Wed, Nov 6, 2024 at 8:02 PM Carlos Llamas <cmllamas@...gle.com> wrote:
>
> The main focus of these patches is to improve the performance of binder
> page installations, primarily by reducing contention on the mmap_lock.
> The idea is to allow concurrent page insertion by leveraging per-vma
> locking and get_user_pages_remote().
>
> Unfortunately, this required reverting the alloc->lock spinlock back
> into a mutex in order to serialize with the shrinker. At least until
> finding a better solution e.g. support page zapping with a spinlock.
> The trade off is still quite worth it though.
>
> Other patches are also included that remove unsafe and redundant things
> such as the alloc->vma pointer or the struct binder_lru_page concept.
>
> Note: I'll work on setting up a page fault handler for binder next.
> I believe an idea from Alice Ryhl to deferred the page insertions will
> make this finally feasible. I only need to figure out a few performance
> bits but if/when done most of the manual page insertion code in binder
> could be dropped. :)
>
> Changelog:
>
> v2:
>  * fix locking order when upgrading from vma lock to mmap lock
>  * switch folio_walk_start() for get_user_pages_remote()
>  * release vma/mmap locks and mmput() right after vm_insert_page()
>  * add binder_page_alloc() helper for binder_install_single_page()
>
> v1:
> https://lore.kernel.org/all/20241105200258.2380168-1-cmllamas@google.com/
>
> Cc: Alice Ryhl <aliceryhl@...gle.com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Liam R. Howlett <Liam.Howlett@...cle.com>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Minchan Kim <minchan@...nel.org>
> Cc: Nhat Pham <nphamcs@...il.com>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Suren Baghdasaryan <surenb@...gle.com>
> Cc: Todd Kjos <tkjos@...gle.com>
> Cc: Viktor Martensson <vmartensson@...gle.com>
> Cc: Hillf Danton <hdanton@...a.com>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

Some nits but overall looks quite good.

Reviewed-by: Suren Baghdasaryan <surenb@...gle.com>

>
> Carlos Llamas (8):
>   Revert "binder: switch alloc->mutex to spinlock_t"
>   binder: concurrent page installation
>   binder: select correct nid for pages in LRU
>   binder: remove struct binder_lru_page
>   binder: use alloc->mapped to save the vma state
>   binder: remove cached alloc->vma pointer
>   binder: rename alloc->buffer to vm_start
>   binder: use per-vma lock in page installation
>
>  drivers/android/binder.c                |   2 +-
>  drivers/android/binder_alloc.c          | 322 ++++++++++++++----------
>  drivers/android/binder_alloc.h          |  35 +--
>  drivers/android/binder_alloc_selftest.c |  18 +-
>  drivers/android/binder_trace.h          |   2 +-
>  5 files changed, 212 insertions(+), 167 deletions(-)
>
> --
> 2.47.0.199.ga7371fff76-goog
>