On 07/06/16 15:24, Grygorii Strashko wrote:
On 06/07/2016 02:52 PM, Tero Kristo wrote:
On 07/06/16 13:08, Herbert Xu wrote:
On Wed, Jun 01, 2016 at 06:03:52PM -0500, Dave Gerlach wrote:
On 06/01/2016 04:53 AM, Grygorii Strashko wrote:
On 06/01/2016 11:56 AM, Tero Kristo wrote:
From: Lokesh Vutla <lokeshvutla@xxxxxx>
Calling runtime PM API for every block causes serious perf hit to
crypto operations that are done on a long buffer.
As crypto is performed on a page boundary, encrypting large buffers
can
cause a series of crypto operations divided by page. The runtime PM
API
is also called those many times.
We call runtime_pm_get_sync only at beginning on the session
(cra_init)
and runtime_pm_put at the end. This result in upto a 50% speedup.
This doesn't make the driver to keep the system awake as runtime
get/put
is only called during a crypto session which completes usually
quickly.
Signed-off-by: Lokesh Vutla <lokeshvutla@xxxxxx>
Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
---
drivers/crypto/omap-sham.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/drivers/crypto/omap-sham.c b/drivers/crypto/omap-sham.c
index 6eefaa2..bd0258f 100644
--- a/drivers/crypto/omap-sham.c
+++ b/drivers/crypto/omap-sham.c
@@ -360,14 +360,6 @@ static void omap_sham_copy_ready_hash(struct
ahash_request *req)
static int omap_sham_hw_init(struct omap_sham_dev *dd)
{
- int err;
-
- err = pm_runtime_get_sync(dd->dev);
- if (err < 0) {
- dev_err(dd->dev, "failed to get sync: %d\n", err);
- return err;
- }
-
Would it be worth it to investigate a pm_runtime autosuspend
approach rather than knocking runtime PM out here completely? I am
not clear if the overhead is coming from the pm_runtime calls
themselves or the actual idling of the IP, but if it's the idling of
the IP causing the slowdown, with a large enough autosuspend_delay
we don't actually sleep between each block but after a long enough
period of idle time we would actually suspend.
Indeed, I think this patch is bogus. cra_init is associated
with the tfm object which is usually long-lived. So doing power
management there makes no sense.
Cheers,
I can investigate this further, but I believe this patch itself gave a
noticeable performance boost.
This is an optimization anyway, and not critical for functionality.
It is not critical only if below code would not introduce races
I don't get your point here. This patch is an optimization, and the
driver works fine without it.
+ spin_lock_bh(&sham.lock);
+ list_for_each_entry(dd, &sham.dev_list, list) {
+ break;
+ }
+ spin_unlock_bh(&sham.lock);
Is it guaranteed that dd will alive always at this moment?
Typically yes, but I think there might be a race condition here if the
driver is removed during operation. Anyway, I'll drop this patch and
change the optimization to use autosuspend as Dave suggested; that gives
almost the same performance boost as this one (I miss a couple of
percent in the overall performance, but I can live with that.)
-Tero
+
+ pm_runtime_get_sync(dd->dev);
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