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Commit 2b163b5b authored by Horia Geantă's avatar Horia Geantă Committed by Herbert Xu
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Revert "crypto: caam - get rid of tasklet" 

This reverts commit 66d2e202.

Quoting from Russell's findings:
https://www.mail-archive.com/linux-crypto@vger.kernel.org/msg21136.html



[quote]
Okay, I've re-tested, using a different way of measuring, because using
openssl speed is impractical for off-loaded engines.  I've decided to
use this way to measure the performance:

dd if=/dev/zero bs=1048576 count=128 | /usr/bin/time openssl dgst -md5

For the threaded IRQs case gives:

0.05user 2.74system 0:05.30elapsed 52%CPU (0avgtext+0avgdata 2400maxresident)k
0.06user 2.52system 0:05.18elapsed 49%CPU (0avgtext+0avgdata 2404maxresident)k
0.12user 2.60system 0:05.61elapsed 48%CPU (0avgtext+0avgdata 2460maxresident)k
	=> 5.36s => 25.0MB/s

and the tasklet case:

0.08user 2.53system 0:04.83elapsed 54%CPU (0avgtext+0avgdata 2468maxresident)k
0.09user 2.47system 0:05.16elapsed 49%CPU (0avgtext+0avgdata 2368maxresident)k
0.10user 2.51system 0:04.87elapsed 53%CPU (0avgtext+0avgdata 2460maxresident)k
	=> 4.95 => 27.1MB/s

which corresponds to an 8% slowdown for the threaded IRQ case.  So,
tasklets are indeed faster than threaded IRQs.

[...]

I think I've proven from the above that this patch needs to be reverted
due to the performance regression, and that there _is_ most definitely
a deterimental effect of switching from tasklets to threaded IRQs.
[/quote]

Signed-off-by: default avatarHoria Geantă <horia.geanta@nxp.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent c73e36e8

drivers/crypto/caam/intern.h

+1 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ struct caam_drv_private_jr { 
	struct device		*dev;

	int ridx;

	struct caam_job_ring __iomem *rregs;	/* JobR's register space */

	struct tasklet_struct irqtask;

	int irq;			/* One per queue */



	/* Number of scatterlist crypt transforms active on the JobR */

drivers/crypto/caam/jr.c

+16 −9
Original line number Diff line number Diff line
@@ -73,6 +73,8 @@ static int caam_jr_shutdown(struct device *dev) 


	ret = caam_reset_hw_jr(dev);



	tasklet_kill(&jrp->irqtask);



	/* Release interrupt */

	free_irq(jrp->irq, dev);
@@ -128,7 +130,7 @@ static irqreturn_t caam_jr_interrupt(int irq, void *st_dev) 


	/*

	 * Check the output ring for ready responses, kick

	 * the threaded irq if jobs done.

	 * tasklet if jobs done.

	 */

	irqstate = rd_reg32(&jrp->rregs->jrintstatus);

	if (!irqstate)
@@ -150,13 +152,18 @@ static irqreturn_t caam_jr_interrupt(int irq, void *st_dev) 
	/* Have valid interrupt at this point, just ACK and trigger */

	wr_reg32(&jrp->rregs->jrintstatus, irqstate);



	return IRQ_WAKE_THREAD;

	preempt_disable();

	tasklet_schedule(&jrp->irqtask);

	preempt_enable();



	return IRQ_HANDLED;

}



static irqreturn_t caam_jr_threadirq(int irq, void *st_dev)

/* Deferred service handler, run as interrupt-fired tasklet */

static void caam_jr_dequeue(unsigned long devarg)

{

	int hw_idx, sw_idx, i, head, tail;

	struct device *dev = st_dev;

	struct device *dev = (struct device *)devarg;

	struct caam_drv_private_jr *jrp = dev_get_drvdata(dev);

	void (*usercall)(struct device *dev, u32 *desc, u32 status, void *arg);

	u32 *userdesc, userstatus;
@@ -230,8 +237,6 @@ static irqreturn_t caam_jr_threadirq(int irq, void *st_dev) 


	/* reenable / unmask IRQs */

	clrsetbits_32(&jrp->rregs->rconfig_lo, JRCFG_IMSK, 0);



	return IRQ_HANDLED;

}



/**
@@ -389,9 +394,10 @@ static int caam_jr_init(struct device *dev) 


	jrp = dev_get_drvdata(dev);



	tasklet_init(&jrp->irqtask, caam_jr_dequeue, (unsigned long)dev);



	/* Connect job ring interrupt handler. */

	error = request_threaded_irq(jrp->irq, caam_jr_interrupt,

				     caam_jr_threadirq, IRQF_SHARED,

	error = request_irq(jrp->irq, caam_jr_interrupt, IRQF_SHARED,

			    dev_name(dev), dev);

	if (error) {

		dev_err(dev, "can't connect JobR %d interrupt (%d)\n",
@@ -454,6 +460,7 @@ static int caam_jr_init(struct device *dev) 
out_free_irq:

	free_irq(jrp->irq, dev);

out_kill_deq:

	tasklet_kill(&jrp->irqtask);

	return error;

}