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authorKim Phillips <kim.phillips@freescale.com>2012-06-22 19:48:53 -0500
committerHerbert Xu <herbert@gondor.apana.org.au>2012-06-27 14:42:06 +0800
commit1a076689cda8a1d623dcda170b2dc2b476cc6f1a (patch)
tree4c71eb88be4803eb8fd3b60884e8e9b2bc496b5e /drivers/crypto
parent281922a1d4f59bdebbe78c1d9f4c50a967eb6cff (diff)
downloadlinux-1a076689cda8a1d623dcda170b2dc2b476cc6f1a.tar.bz2
crypto: caam - disable IRQ coalescing by default
It has been observed that in zero-loss benchmarks, when a slow traffic rate is being tested, the IRQ timer coalescing parameter was set too high, and the ethernet controller would start dropping packets because the job ring back half wouldn't be executed in time before the ethernet controller would fill its buffers, thereby significantly reducing the zero-loss performance figures. Empirical testing has shown that the best zero-loss performance is achieved when IRQ coalescing is set to minimum values and/or turned off, since apparently the job ring driver already implements an adequately-performing general-purpose IRQ mitigation strategy in software. Whilst we could go with minimal count (2-8) and timing settings (192-256), we prefer just turning h/w coalescing altogether off to minimize setkey latency (due to split key generation), and for consistent cross-SoC performance (the SEC vs. core clock ratio changes). Signed-off-by: Kim Phillips <kim.phillips@freescale.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/crypto')
-rw-r--r--drivers/crypto/caam/Kconfig5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/crypto/caam/Kconfig b/drivers/crypto/caam/Kconfig
index 502a7f3cca5f..65c7668614ab 100644
--- a/drivers/crypto/caam/Kconfig
+++ b/drivers/crypto/caam/Kconfig
@@ -32,10 +32,13 @@ config CRYPTO_DEV_FSL_CAAM_RINGSIZE
config CRYPTO_DEV_FSL_CAAM_INTC
bool "Job Ring interrupt coalescing"
depends on CRYPTO_DEV_FSL_CAAM
- default y
+ default n
help
Enable the Job Ring's interrupt coalescing feature.
+ Note: the driver already provides adequate
+ interrupt coalescing in software.
+
config CRYPTO_DEV_FSL_CAAM_INTC_COUNT_THLD
int "Job Ring interrupt coalescing count threshold"
depends on CRYPTO_DEV_FSL_CAAM_INTC