* Re: [PATCH] rust: sync: rcu: Mark Guard methods as inline
2025-03-12 10:17 [PATCH] rust: sync: rcu: Mark Guard methods as inline I Hsin Cheng
@ 2025-03-12 11:48 ` Benno Lossin
2025-03-12 12:20 ` Charalampos Mitrodimas
` (2 subsequent siblings)
3 siblings, 0 replies; 7+ messages in thread
From: Benno Lossin @ 2025-03-12 11:48 UTC (permalink / raw)
To: I Hsin Cheng, rostedt
Cc: paulmck, frederic, neeraj.upadhyay, joel, josh, boqun.feng,
urezki, mathieu.desnoyers, jiangshanlai, qiang.zhang1211, ojeda,
alex.gaynor, gary, bjorn3_gh, a.hindborg, aliceryhl, tmgross,
dakr, rcu, rust-for-linux, linux-kernel, skhan, jserv
On Wed Mar 12, 2025 at 11:17 AM CET, I Hsin Cheng wrote:
> Currenyly the implementation of "Guard" methods are basically wrappers
> around rcu's function within kernel. Building the kernel with llvm
> 18.1.8 on x86_64 machine will generate the following symbols:
>
> $ nm vmlinux | grep ' _R'.*Guard | rustfilt
> ffffffff817b6c90 T <kernel::sync::rcu::Guard>::new
> ffffffff817b6cb0 T <kernel::sync::rcu::Guard>::unlock
> ffffffff817b6cd0 T <kernel::sync::rcu::Guard as core::ops::drop::Drop>::drop
> ffffffff817b6c90 T <kernel::sync::rcu::Guard as core::default::Default>::default
>
> These Rust symbols are basically wrappers around functions
> "rcu_read_lock" and "rcu_read_unlock". Marking them as inline can
> reduce the generation of these symbols, and saves the size of code
> generation for 100 bytes.
>
> $ ./scripts/bloat-o-meter vmlinux_old vmlinux_new
> add/remove: 0/8 grow/shrink: 0/0 up/down: 0/-100 (-100)
> Function old new delta
> _RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 9 - -9
> _RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 9 - -9
> __pfx__RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 16 - -16
> __pfx__RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 16 - -16
> Total: Before=23385830, After=23385730, chg -0.00%
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
---
Cheers,
Benno
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] rust: sync: rcu: Mark Guard methods as inline
2025-03-12 10:17 [PATCH] rust: sync: rcu: Mark Guard methods as inline I Hsin Cheng
2025-03-12 11:48 ` Benno Lossin
@ 2025-03-12 12:20 ` Charalampos Mitrodimas
2025-03-13 4:30 ` Joel Fernandes
2025-03-13 19:41 ` Christian Schrefl
3 siblings, 0 replies; 7+ messages in thread
From: Charalampos Mitrodimas @ 2025-03-12 12:20 UTC (permalink / raw)
To: I Hsin Cheng
Cc: rostedt, paulmck, frederic, neeraj.upadhyay, joel, josh,
boqun.feng, urezki, mathieu.desnoyers, jiangshanlai,
qiang.zhang1211, ojeda, alex.gaynor, gary, bjorn3_gh,
benno.lossin, a.hindborg, aliceryhl, tmgross, dakr, rcu,
rust-for-linux, linux-kernel, skhan, jserv
I Hsin Cheng <richard120310@gmail.com> writes:
> Currenyly the implementation of "Guard" methods are basically wrappers
"Currenyly" -> "Currently".
> around rcu's function within kernel. Building the kernel with llvm
> 18.1.8 on x86_64 machine will generate the following symbols:
>
> $ nm vmlinux | grep ' _R'.*Guard | rustfilt
> ffffffff817b6c90 T <kernel::sync::rcu::Guard>::new
> ffffffff817b6cb0 T <kernel::sync::rcu::Guard>::unlock
> ffffffff817b6cd0 T <kernel::sync::rcu::Guard as core::ops::drop::Drop>::drop
> ffffffff817b6c90 T <kernel::sync::rcu::Guard as core::default::Default>::default
>
> These Rust symbols are basically wrappers around functions
> "rcu_read_lock" and "rcu_read_unlock". Marking them as inline can
> reduce the generation of these symbols, and saves the size of code
> generation for 100 bytes.
>
> $ ./scripts/bloat-o-meter vmlinux_old vmlinux_new
> add/remove: 0/8 grow/shrink: 0/0 up/down: 0/-100 (-100)
> Function old new delta
> _RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 9 - -9
> _RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 9 - -9
> __pfx__RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 16 - -16
> __pfx__RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 16 - -16
> Total: Before=23385830, After=23385730, chg -0.00%
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
Reviewed-by: Charalampos Mitrodimas <charmitro@posteo.net>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] rust: sync: rcu: Mark Guard methods as inline
2025-03-12 10:17 [PATCH] rust: sync: rcu: Mark Guard methods as inline I Hsin Cheng
2025-03-12 11:48 ` Benno Lossin
2025-03-12 12:20 ` Charalampos Mitrodimas
@ 2025-03-13 4:30 ` Joel Fernandes
2025-03-14 14:43 ` Miguel Ojeda
2025-03-13 19:41 ` Christian Schrefl
3 siblings, 1 reply; 7+ messages in thread
From: Joel Fernandes @ 2025-03-13 4:30 UTC (permalink / raw)
To: I Hsin Cheng
Cc: rostedt, paulmck, frederic, neeraj.upadhyay, joel, josh,
boqun.feng, urezki, mathieu.desnoyers, jiangshanlai,
qiang.zhang1211, ojeda, alex.gaynor, gary, bjorn3_gh,
benno.lossin, a.hindborg, aliceryhl, tmgross, dakr, rcu,
rust-for-linux, linux-kernel, skhan, jserv
On Wed, Mar 12, 2025 at 06:17:23PM +0800, I Hsin Cheng wrote:
> Currenyly the implementation of "Guard" methods are basically wrappers
> around rcu's function within kernel. Building the kernel with llvm
> 18.1.8 on x86_64 machine will generate the following symbols:
>
> $ nm vmlinux | grep ' _R'.*Guard | rustfilt
> ffffffff817b6c90 T <kernel::sync::rcu::Guard>::new
> ffffffff817b6cb0 T <kernel::sync::rcu::Guard>::unlock
> ffffffff817b6cd0 T <kernel::sync::rcu::Guard as core::ops::drop::Drop>::drop
> ffffffff817b6c90 T <kernel::sync::rcu::Guard as core::default::Default>::default
>
> These Rust symbols are basically wrappers around functions
> "rcu_read_lock" and "rcu_read_unlock". Marking them as inline can
> reduce the generation of these symbols, and saves the size of code
> generation for 100 bytes.
>
> $ ./scripts/bloat-o-meter vmlinux_old vmlinux_new
> add/remove: 0/8 grow/shrink: 0/0 up/down: 0/-100 (-100)
> Function old new delta
> _RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 9 - -9
> _RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 9 - -9
> __pfx__RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 16 - -16
> __pfx__RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 16 - -16
> Total: Before=23385830, After=23385730, chg -0.00%
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
> ---
> rust/kernel/sync/rcu.rs | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/rust/kernel/sync/rcu.rs b/rust/kernel/sync/rcu.rs
> index b51d9150ffe2..26df2a6cb09f 100644
> --- a/rust/kernel/sync/rcu.rs
> +++ b/rust/kernel/sync/rcu.rs
> @@ -17,6 +17,7 @@
>
> impl Guard {
> /// Acquires the RCU read side lock and returns a guard.
> + #[inline]
> pub fn new() -> Self {
> // SAFETY: An FFI call with no additional requirements.
> unsafe { bindings::rcu_read_lock() };
> @@ -25,16 +26,19 @@ pub fn new() -> Self {
> }
>
> /// Explicitly releases the RCU read side lock.
> + #[inline]
> pub fn unlock(self) {}
> }
>
> impl Default for Guard {
> + #[inline]
> fn default() -> Self {
> Self::new()
> }
> }
>
> impl Drop for Guard {
> + #[inline]
> fn drop(&mut self) {
> // SAFETY: By the type invariants, the RCU read side is locked, so it is ok to unlock it.
> unsafe { bindings::rcu_read_unlock() };
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
If no objections, I can queue it for 6.16 but let me know if Rust maintainers
prefer to take it.
thanks,
- Joel
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH] rust: sync: rcu: Mark Guard methods as inline
2025-03-13 4:30 ` Joel Fernandes
@ 2025-03-14 14:43 ` Miguel Ojeda
2025-03-15 6:29 ` I Hsin Cheng
0 siblings, 1 reply; 7+ messages in thread
From: Miguel Ojeda @ 2025-03-14 14:43 UTC (permalink / raw)
To: Joel Fernandes
Cc: I Hsin Cheng, rostedt, paulmck, frederic, neeraj.upadhyay, joel,
josh, boqun.feng, urezki, mathieu.desnoyers, jiangshanlai,
qiang.zhang1211, ojeda, alex.gaynor, gary, bjorn3_gh,
benno.lossin, a.hindborg, aliceryhl, tmgross, dakr, rcu,
rust-for-linux, linux-kernel, skhan, jserv
On Thu, Mar 13, 2025 at 5:30 AM Joel Fernandes <joelagnelf@nvidia.com> wrote:
>
> Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
>
> If no objections, I can queue it for 6.16 but let me know if Rust maintainers
> prefer to take it.
Thanks! That would be great -- FWIW:
Acked-by: Miguel Ojeda <ojeda@kernel.org>
By the way, should `read_lock()` be marked too? It just calls another
(now `#[inline]` one).
Cheers,
Miguel
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] rust: sync: rcu: Mark Guard methods as inline
2025-03-14 14:43 ` Miguel Ojeda
@ 2025-03-15 6:29 ` I Hsin Cheng
0 siblings, 0 replies; 7+ messages in thread
From: I Hsin Cheng @ 2025-03-15 6:29 UTC (permalink / raw)
To: Miguel Ojeda
Cc: Joel Fernandes, rostedt, paulmck, frederic, neeraj.upadhyay, joel,
josh, boqun.feng, urezki, mathieu.desnoyers, jiangshanlai,
qiang.zhang1211, ojeda, alex.gaynor, gary, bjorn3_gh,
benno.lossin, a.hindborg, aliceryhl, tmgross, dakr, rcu,
rust-for-linux, linux-kernel, skhan, jserv
On Fri, Mar 14, 2025 at 03:43:23PM +0100, Miguel Ojeda wrote:
> On Thu, Mar 13, 2025 at 5:30 AM Joel Fernandes <joelagnelf@nvidia.com> wrote:
> >
> > Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
> >
> > If no objections, I can queue it for 6.16 but let me know if Rust maintainers
> > prefer to take it.
>
> Thanks! That would be great -- FWIW:
>
> Acked-by: Miguel Ojeda <ojeda@kernel.org>
>
> By the way, should `read_lock()` be marked too? It just calls another
> (now `#[inline]` one).
>
> Cheers,
> Miguel
Hi all,
Thanks for your kindly review and comments!
> By the way, should `read_lock()` be marked too? It just calls another
> (now `#[inline]` one).
I'll do it and fix the typo mentioned by Charalampos. I'll send v2 to
you ASAP. Thanks !
Best regards,
I Hsin Cheng
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] rust: sync: rcu: Mark Guard methods as inline
2025-03-12 10:17 [PATCH] rust: sync: rcu: Mark Guard methods as inline I Hsin Cheng
` (2 preceding siblings ...)
2025-03-13 4:30 ` Joel Fernandes
@ 2025-03-13 19:41 ` Christian Schrefl
3 siblings, 0 replies; 7+ messages in thread
From: Christian Schrefl @ 2025-03-13 19:41 UTC (permalink / raw)
To: I Hsin Cheng, rostedt
Cc: paulmck, frederic, neeraj.upadhyay, joel, josh, boqun.feng,
urezki, mathieu.desnoyers, jiangshanlai, qiang.zhang1211, ojeda,
alex.gaynor, gary, bjorn3_gh, benno.lossin, a.hindborg, aliceryhl,
tmgross, dakr, rcu, rust-for-linux, linux-kernel, skhan, jserv
On 12.03.25 11:17 AM, I Hsin Cheng wrote:
> Currenyly the implementation of "Guard" methods are basically wrappers
> around rcu's function within kernel. Building the kernel with llvm
> 18.1.8 on x86_64 machine will generate the following symbols:
>
> $ nm vmlinux | grep ' _R'.*Guard | rustfilt
> ffffffff817b6c90 T <kernel::sync::rcu::Guard>::new
> ffffffff817b6cb0 T <kernel::sync::rcu::Guard>::unlock
> ffffffff817b6cd0 T <kernel::sync::rcu::Guard as core::ops::drop::Drop>::drop
> ffffffff817b6c90 T <kernel::sync::rcu::Guard as core::default::Default>::default
>
> These Rust symbols are basically wrappers around functions
> "rcu_read_lock" and "rcu_read_unlock". Marking them as inline can
> reduce the generation of these symbols, and saves the size of code
> generation for 100 bytes.
>
> $ ./scripts/bloat-o-meter vmlinux_old vmlinux_new
> add/remove: 0/8 grow/shrink: 0/0 up/down: 0/-100 (-100)
> Function old new delta
> _RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 9 - -9
> _RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 9 - -9
> _RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 9 - -9
> __pfx__RNvXs_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB4_5GuardNtNtCsdaXADs8PRFB_4core7default7Default7default 16 - -16
> __pfx__RNvXs0_NtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB5_5GuardNtNtNtCsdaXADs8PRFB_4core3ops4drop4Drop4drop 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard6unlock 16 - -16
> __pfx__RNvMNtNtCsaYBeKL739Xz_6kernel4sync3rcuNtB2_5Guard3new 16 - -16
> Total: Before=23385830, After=23385730, chg -0.00%
>
> Link: https://github.com/Rust-for-Linux/linux/issues/1145
> Signed-off-by: I Hsin Cheng <richard120310@gmail.com>
> ---Reviewed-by: Christian Schrefl <chrisi.schrefl@gmail.com>
Cheers
Christian
^ permalink raw reply [flat|nested] 7+ messages in thread