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%3Ba=su...
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@vger.kernel.org know about it.
From 2b163b5bce04546da72617bfb6c8bf07a45c4b17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Horia=20Geant=C4=83?= horia.geanta@nxp.com Date: Wed, 9 Nov 2016 10:46:21 +0200 Subject: Revert "crypto: caam - get rid of tasklet" MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit
From: Horia Geantă horia.geanta@nxp.com
commit 2b163b5bce04546da72617bfb6c8bf07a45c4b17 upstream.
This reverts commit 66d2e2028091a074aa1290d2eeda5ddb1a6c329c.
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: Horia Geantă horia.geanta@nxp.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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@nxp.com are
queue-4.9/revert-crypto-caam-get-rid-of-tasklet.patch