[v6,0/2] use static key to optimize pgtable_l4_enabled

Message

Jisheng Zhang July 16, 2022, 11:50 a.m. UTC

The pgtable_l4|[l5]_enabled check sits at hot code path, performance
is impacted a lot. Since pgtable_l4|[l5]_enabled isn't changed after
boot, so static key can be used to solve the performance issue[1].

An unified way static key was introduced in [2], but it only targets
riscv isa extension. We dunno whether SV48 and SV57 will be considered
as isa extension, so the unified solution isn't used for
pgtable_l4[l5]_enabled now.

patch1 fixes a NULL pointer deference if static key is used a bit earlier.
patch2 uses the static key to optimize pgtable_l4|[l5]_enabled.

[1] http://lists.infradead.org/pipermail/linux-riscv/2021-December/011164.html
[2] https://lore.kernel.org/linux-riscv/[e-mail]/T/#t

Since v5:
 - Use DECLARE_STATIC_KEY_FALSE

Since v4:
 - rebased on v5.19-rcN
 - collect Reviewed-by tags
 - Fix kernel panic issue if SPARSEMEM is enabled by moving the
   riscv_finalise_pgtable_lx() after sparse_init()

Since v3:
 - fix W=1 call to undeclared function 'static_branch_likely' error

Since v2:
 - move the W=1 warning fix to a separate patch
 - move the unified way to use static key to a new patch series.

Since v1:
 - Add a W=1 warning fix
 - Fix W=1 error
 - Based on v5.18-rcN, since SV57 support is added, so convert
   pgtable_l5_enabled as well.

Jisheng Zhang (2):
  riscv: move sbi_init() earlier before jump_label_init()
  riscv: turn pgtable_l4|[l5]_enabled to static key for RV64

 arch/riscv/include/asm/pgalloc.h    | 16 ++++----
 arch/riscv/include/asm/pgtable-32.h |  3 ++
 arch/riscv/include/asm/pgtable-64.h | 60 ++++++++++++++++++---------
 arch/riscv/include/asm/pgtable.h    |  5 +--
 arch/riscv/kernel/cpu.c             |  4 +-
 arch/riscv/kernel/setup.c           |  2 +-
 arch/riscv/mm/init.c                | 64 ++++++++++++++++++-----------
 arch/riscv/mm/kasan_init.c          | 16 ++++----
 8 files changed, 104 insertions(+), 66 deletions(-)

Comments

Jisheng Zhang Aug. 14, 2022, 1:53 a.m. UTC | #1

On Sat, Jul 16, 2022 at 07:50:57PM +0800, Jisheng Zhang wrote:
> The pgtable_l4|[l5]_enabled check sits at hot code path, performance
> is impacted a lot. Since pgtable_l4|[l5]_enabled isn't changed after
> boot, so static key can be used to solve the performance issue[1].
> 
> An unified way static key was introduced in [2], but it only targets
> riscv isa extension. We dunno whether SV48 and SV57 will be considered
> as isa extension, so the unified solution isn't used for
> pgtable_l4[l5]_enabled now.
> 
> patch1 fixes a NULL pointer deference if static key is used a bit earlier.
> patch2 uses the static key to optimize pgtable_l4|[l5]_enabled.
> 
> [1] http://lists.infradead.org/pipermail/linux-riscv/2021-December/011164.html
> [2] https://lore.kernel.org/linux-riscv/[e-mail]/T/#t

Hi Palmer,

I see part1 and part2 were sent out...
What I can do to make this series merged for 6.0-rc1? I'm afraid this series
may miss anothe round of merge window again.

Thanks in advance

> 
> Since v5:
>  - Use DECLARE_STATIC_KEY_FALSE
> 
> Since v4:
>  - rebased on v5.19-rcN
>  - collect Reviewed-by tags
>  - Fix kernel panic issue if SPARSEMEM is enabled by moving the
>    riscv_finalise_pgtable_lx() after sparse_init()
> 
> Since v3:
>  - fix W=1 call to undeclared function 'static_branch_likely' error
> 
> Since v2:
>  - move the W=1 warning fix to a separate patch
>  - move the unified way to use static key to a new patch series.
> 
> Since v1:
>  - Add a W=1 warning fix
>  - Fix W=1 error
>  - Based on v5.18-rcN, since SV57 support is added, so convert
>    pgtable_l5_enabled as well.
> 
> Jisheng Zhang (2):
>   riscv: move sbi_init() earlier before jump_label_init()
>   riscv: turn pgtable_l4|[l5]_enabled to static key for RV64
> 
>  arch/riscv/include/asm/pgalloc.h    | 16 ++++----
>  arch/riscv/include/asm/pgtable-32.h |  3 ++
>  arch/riscv/include/asm/pgtable-64.h | 60 ++++++++++++++++++---------
>  arch/riscv/include/asm/pgtable.h    |  5 +--
>  arch/riscv/kernel/cpu.c             |  4 +-
>  arch/riscv/kernel/setup.c           |  2 +-
>  arch/riscv/mm/init.c                | 64 ++++++++++++++++++-----------
>  arch/riscv/mm/kasan_init.c          | 16 ++++----
>  8 files changed, 104 insertions(+), 66 deletions(-)
> 
> -- 
> 2.34.1
> 
> 
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