On 07/06/16 15:24, Grygorii Strashko wrote:

On 06/07/2016 02:52 PM, Tero Kristo wrote:

quoted

On 07/06/16 13:08, Herbert Xu wrote:

quoted

On Wed, Jun 01, 2016 at 06:03:52PM -0500, Dave Gerlach wrote:

quoted

On 06/01/2016 04:53 AM, Grygorii Strashko wrote:

quoted

On 06/01/2016 11:56 AM, Tero Kristo wrote:

quoted

From: Lokesh Vutla <redacted>

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 <redacted>
Signed-off-by: Tero Kristo <redacted>
---
  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);