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Message-ID: <20120308192507.GM2348@linux.vnet.ibm.com>
Date: Thu, 8 Mar 2012 11:25:07 -0800
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Lai Jiangshan <laijs@...fujitsu.com>
Cc: linux-kernel@...r.kernel.org, mingo@...e.hu, dipankar@...ibm.com,
akpm@...ux-foundation.org, mathieu.desnoyers@...ymtl.ca,
josh@...htriplett.org, niv@...ibm.com, tglx@...utronix.de,
peterz@...radead.org, rostedt@...dmis.org, Valdis.Kletnieks@...edu,
dhowells@...hat.com, eric.dumazet@...il.com, darren@...art.com,
fweisbec@...il.com, patches@...aro.org
Subject: Re: [PATCH 3/6] use "int trycount" instead of "bool expedited"
On Tue, Mar 06, 2012 at 05:57:35PM +0800, Lai Jiangshan wrote:
> Signed-off-by: Lai Jiangshan <laijs@...fujitsu.com>
This looks good, but does not apply. I will push to -rcu, and then you
can tell me what I am missing.
Thanx, Paul
> ---
> kernel/srcu.c | 27 ++++++++++++++-------------
> 1 files changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/kernel/srcu.c b/kernel/srcu.c
> index fbe2d5f..d5f3450 100644
> --- a/kernel/srcu.c
> +++ b/kernel/srcu.c
> @@ -254,12 +254,12 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock);
> * we repeatedly block for 1-millisecond time periods. This approach
> * has done well in testing, so there is no need for a config parameter.
> */
> -#define SYNCHRONIZE_SRCU_READER_DELAY 5
> +#define SYNCHRONIZE_SRCU_READER_DELAY 5
> +#define SYNCHRONIZE_SRCU_TRYCOUNT 2
> +#define SYNCHRONIZE_SRCU_EXP_TRYCOUNT 12
>
> -static void wait_idx(struct srcu_struct *sp, int idx, bool expedited)
> +static void wait_idx(struct srcu_struct *sp, int idx, int trycount)
> {
> - int trycount = 0;
> -
> /*
> * If a reader fetches the index before the ->completed increment,
> * but increments its counter after srcu_readers_active_idx_check()
> @@ -278,9 +278,10 @@ static void wait_idx(struct srcu_struct *sp, int idx, bool expedited)
> if (!srcu_readers_active_idx_check(sp, idx)) {
> udelay(SYNCHRONIZE_SRCU_READER_DELAY);
> while (!srcu_readers_active_idx_check(sp, idx)) {
> - if (expedited && ++ trycount < 10)
> + if (trycount > 0) {
> + trycount--;
> udelay(SYNCHRONIZE_SRCU_READER_DELAY);
> - else
> + } else
> schedule_timeout_interruptible(1);
> }
> }
> @@ -310,18 +311,18 @@ static void wait_idx(struct srcu_struct *sp, int idx, bool expedited)
> * by the next __synchronize_srcu() invoking wait_idx() for such readers
> * before starting a new grace period.
> */
> -static void flip_idx_and_wait(struct srcu_struct *sp, bool expedited)
> +static void flip_idx_and_wait(struct srcu_struct *sp, int trycount)
> {
> int idx;
>
> idx = sp->completed++ & 0x1;
> - wait_idx(sp, idx, expedited);
> + wait_idx(sp, idx, trycount);
> }
>
> /*
> * Helper function for synchronize_srcu() and synchronize_srcu_expedited().
> */
> -static void __synchronize_srcu(struct srcu_struct *sp, bool expedited)
> +static void __synchronize_srcu(struct srcu_struct *sp, int trycount)
> {
> rcu_lockdep_assert(!lock_is_held(&sp->dep_map) &&
> !lock_is_held(&rcu_bh_lock_map) &&
> @@ -357,14 +358,14 @@ static void __synchronize_srcu(struct srcu_struct *sp, bool expedited)
> * fetching ->completed and incrementing their counter, wait_idx()
> * will normally not need to wait.
> */
> - wait_idx(sp, (sp->completed - 1) & 0x1, expedited);
> + wait_idx(sp, (sp->completed - 1) & 0x1, trycount);
>
> /*
> * Now that wait_idx() has waited for the really old readers,
> * invoke flip_idx_and_wait() to flip the counter and wait
> * for current SRCU readers.
> */
> - flip_idx_and_wait(sp, expedited);
> + flip_idx_and_wait(sp, trycount);
>
> mutex_unlock(&sp->mutex);
> }
> @@ -385,7 +386,7 @@ static void __synchronize_srcu(struct srcu_struct *sp, bool expedited)
> */
> void synchronize_srcu(struct srcu_struct *sp)
> {
> - __synchronize_srcu(sp, 0);
> + __synchronize_srcu(sp, SYNCHRONIZE_SRCU_TRYCOUNT);
> }
> EXPORT_SYMBOL_GPL(synchronize_srcu);
>
> @@ -406,7 +407,7 @@ EXPORT_SYMBOL_GPL(synchronize_srcu);
> */
> void synchronize_srcu_expedited(struct srcu_struct *sp)
> {
> - __synchronize_srcu(sp, 1);
> + __synchronize_srcu(sp, SYNCHRONIZE_SRCU_EXP_TRYCOUNT);
> }
> EXPORT_SYMBOL_GPL(synchronize_srcu_expedited);
>
> --
> 1.7.4.4
>
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