This is a note to let you know that I've just added the patch titled
Revert "crypto: caam - get rid of tasklet"
to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
revert-crypto-caam-get-rid-of-tasklet.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 2b163b5bce04546da72617bfb6c8bf07a45c4b17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Horia=20Geant=C4=83?= <horia.geanta@xxxxxxx>
Date: Wed, 9 Nov 2016 10:46:21 +0200
Subject: Revert "crypto: caam - get rid of tasklet"
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From: Horia Geantă <horia.geanta@xxxxxxx>
commit 2b163b5bce04546da72617bfb6c8bf07a45c4b17 upstream.
This reverts commit 66d2e2028091a074aa1290d2eeda5ddb1a6c329c.
Quoting from Russell's findings:
https://www.mail-archive.com/linux-crypto@xxxxxxxxxxxxxxx/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: Horia Geantă <horia.geanta@xxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/crypto/caam/intern.h | 1 +
drivers/crypto/caam/jr.c | 25 ++++++++++++++++---------
2 files changed, 17 insertions(+), 9 deletions(-)
--- a/drivers/crypto/caam/intern.h
+++ b/drivers/crypto/caam/intern.h
@@ -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 */
--- a/drivers/crypto/caam/jr.c
+++ b/drivers/crypto/caam/jr.c
@@ -73,6 +73,8 @@ static int caam_jr_shutdown(struct devic
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
/*
* 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
/* 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
/* reenable / unmask IRQs */
clrsetbits_32(&jrp->rregs->rconfig_lo, JRCFG_IMSK, 0);
-
- return IRQ_HANDLED;
}
/**
@@ -389,10 +394,11 @@ static int caam_jr_init(struct device *d
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,
- dev_name(dev), dev);
+ 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",
jrp->ridx, jrp->irq);
@@ -454,6 +460,7 @@ out_free_inpring:
out_free_irq:
free_irq(jrp->irq, dev);
out_kill_deq:
+ tasklet_kill(&jrp->irqtask);
return error;
}
Patches currently in stable-queue which might be from horia.geanta@xxxxxxx are
queue-4.9/revert-crypto-caam-get-rid-of-tasklet.patch