RE: [PATCH] crypto: caam/jr - optimize job ring enqueue and dequeue operations

[Vakul Garg <vakul.garg@nxp.com>]

> -----Original Message-----
> From: Horia Geanta
> Sent: Tuesday, March 5, 2019 10:14 PM
> To: Vakul Garg <vakul.garg@nxp.com>; linux-crypto@vger.kernel.org
> Cc: Aymen Sghaier <aymen.sghaier@nxp.com>;
> herbert@gondor.apana.org.au; davem@davemloft.net
> Subject: Re: [PATCH] crypto: caam/jr - optimize job ring enqueue and
> dequeue operations
> 
> On 3/5/2019 9:00 AM, Vakul Garg wrote:
> > Instead of reading job ring's occupancy registers for every req/rsp
> > enqueued/dequeued respectively, we read these registers once and store
> > them in memory. After completing a job enqueue/dequeue, we decrement
> > these values. When these values become zero, we refresh the snapshot
> > of job ring's occupancy registers. This eliminates need of expensive
> > device register read operations for every job enqueued and dequeued
> > and hence makes caam_jr_enqueue() and caam_jr_dequeue() faster.
> >
> How expensive?
> Please share the case you benchmarked and performance improvement you
> noticed.

The performance of kernel ipsec improved by about 6% on ls1028.

> 
> Somewhat related: it seems that after commit a0ca6ca022ac ("crypto: caam
> - one tasklet per job ring") the "outlock" spinlock could be removed, this
> being a good candidate for further improvement.
> 
Yes, I remember I discussed it before. 
There are other inefficiencies as well.
Will submit patches. 

> > Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
> > ---
> >  drivers/crypto/caam/intern.h |  1 +
> >  drivers/crypto/caam/jr.c     | 12 ++++++++++--
> >  2 files changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/crypto/caam/intern.h
> > b/drivers/crypto/caam/intern.h index 5869ad58d497..b6d96e2ecf4c
> 100644
> > --- a/drivers/crypto/caam/intern.h
> > +++ b/drivers/crypto/caam/intern.h
> > @@ -59,6 +59,7 @@ struct caam_drv_private_jr {
> >  	int out_ring_read_index;	/* Output index "tail" */
> >  	int tail;			/* entinfo (s/w ring) tail index */
> >  	struct jr_outentry *outring;	/* Base of output ring, DMA-safe */
> > +	u32 inpring_avail;		/* Number of free entries in i/p
> ring*/
> Locality: this should be near the other enqueue-related structure members.
> 
> Nitpick: use "input" instead of "i/p".
> 

Sending v2. 

> Thanks,
> Horia