lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Mon, 26 Nov 2012 10:10:45 +0100 From: Giuseppe CAVALLARO <peppe.cavallaro@...com> To: netdev@...r.kernel.org Cc: bhutchings@...arflare.com, davem@...emloft.net, Giuseppe Cavallaro <peppe.cavallaro@...com> Subject: [net-next.git 5/6] stmmac: update the doc with new IRQ mitigation This patch updates the stmmac.txt adding some information about the new rx/tx mitigation schema adopted in the driver. Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@...com> --- Documentation/networking/stmmac.txt | 28 +++++++++++++++------------- 1 files changed, 15 insertions(+), 13 deletions(-) diff --git a/Documentation/networking/stmmac.txt b/Documentation/networking/stmmac.txt index ef9ee71..f9fa6db 100644 --- a/Documentation/networking/stmmac.txt +++ b/Documentation/networking/stmmac.txt @@ -29,11 +29,9 @@ The kernel configuration option is STMMAC_ETH: dma_txsize: DMA tx ring size; buf_sz: DMA buffer size; tc: control the HW FIFO threshold; - tx_coe: Enable/Disable Tx Checksum Offload engine; watchdog: transmit timeout (in milliseconds); flow_ctrl: Flow control ability [on/off]; pause: Flow Control Pause Time; - tmrate: timer period (only if timer optimisation is configured). 3) Command line options Driver parameters can be also passed in command line by using: @@ -60,17 +58,19 @@ Then the poll method will be scheduled at some future point. The incoming packets are stored, by the DMA, in a list of pre-allocated socket buffers in order to avoid the memcpy (Zero-copy). -4.3) Timer-Driver Interrupt -Instead of having the device that asynchronously notifies the frame receptions, -the driver configures a timer to generate an interrupt at regular intervals. -Based on the granularity of the timer, the frames that are received by the -device will experience different levels of latency. Some NICs have dedicated -timer device to perform this task. STMMAC can use either the RTC device or the -TMU channel 2 on STLinux platforms. -The timers frequency can be passed to the driver as parameter; when change it, -take care of both hardware capability and network stability/performance impact. -Several performance tests on STM platforms showed this optimisation allows to -spare the CPU while having the maximum throughput. +4.3) Interrupt Mitigation +The driver is able to mitigate the number of its DMA interrupts +using NAPI for the reception on chips older than the 3.50. +New chips have an HW RX-Watchdog used for this mitigation. + +On Tx-side, the mitigation schema is based on a SW timer that calls the +tx function (stmmac_tx) to reclaim the resource after transmitting the +frames. +Also there is another parameter (like a threshold) used to program +the descriptors avoiding to set the interrupt on completion bit in +when the frame is sent (xmit). + +Mitigation parameters can be tuned by ethtool. 4.4) WOL Wake up on Lan feature through Magic and Unicast frames are supported for the @@ -121,6 +121,7 @@ struct plat_stmmacenet_data { int bugged_jumbo; int pmt; int force_sf_dma_mode; + int riwt_off; void (*fix_mac_speed)(void *priv, unsigned int speed); void (*bus_setup)(void __iomem *ioaddr); int (*init)(struct platform_device *pdev); @@ -156,6 +157,7 @@ Where: o pmt: core has the embedded power module (optional). o force_sf_dma_mode: force DMA to use the Store and Forward mode instead of the Threshold. + o riwt_off: force to disable the RX watchdog feature and switch to NAPI mode. o fix_mac_speed: this callback is used for modifying some syscfg registers (on ST SoCs) according to the link speed negotiated by the physical layer . -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists