Linux (2.4.20) has only 4 softirqs: HI_SOFTIRQ; NET_TX_SOFTIRQ and NET_RX_SOFTIRQ; TASKLET_SOFTIRQ; Relevant for Linux DDE are for now only the first and the latter - NET_* softirqs allow transparent mutli-threading in Linux' network code. HI_SOFTIRQ is for high priority bottom halves as old-style BHs and sound related drivers.
Understanding the Linux Kernel, Second Edition Softirqs used in Linux 2.4 The index of a sofirq determines its priority: a lower index means higher priority because softirq functions will be executed starting from index 0. The main data structure used to represent softirqs is the softirq_vec array, which includes 32 elements of type softirq_action. linux kernel - Difference between SoftIRQs and Tasklets While studying Linux interrupt handling I found that Tasklets and SoftIRQs are two different methods of performing "bottom half" (lesser priority work). I understand this (quite genuine need). Difference being, SoftIRQs are re-entarant while a Tasklet is NOT. That same SoftIRQ can run on different CPUs while this is NOT the case with Tasklets. softirq | Linux.org New Linux.org Feature: Credits - click here. Tags. softirq. Extremely high softirq load > 90 % when DoS attacking embedded device. Dear I am trying to make my embedded device robust against DoS attack but I notice that the system has a tremendously high softirq load causing the system to hang completely. High Performance Linux: Linux: scaling softirq among many
Jun 11, 2010
Oct 17, 2012 · The Linux kernel's software interrupt ("softirq") mechanism is a bit of a strange beast. It is an obscure holdover from the earliest days of Linux and a mechanism that few kernel developers ever deal with directly. Yet it is at the core of much of the kernel's most important processing. * The two things to balance is latency against fairness - * we want to handle softirqs as soon as possible, but they * should not be able to lock up the box. */ #define MAX_SOFTIRQ_TIME msecs_to_jiffies(2) #define MAX_SOFTIRQ_RESTART 10 #ifdef CONFIG_TRACE_IRQFLAGS /* * When we run softirqs from irq_exit() and thus on the hardirq stack we need softirq Extremely high softirq load > 90 % when DoS attacking embedded device Dear I am trying to make my embedded device robust against DoS attack but I notice that the system has a tremendously high softirq load causing the system to hang completely.
- If a softirq needs serialization, let it serialize itself by its own spinlocks. - Even if softirq is serialized, only local cpu is marked for execution. Hence, we get something sort of weak cpu binding. Though it is still not clear, will it result in better locality or will not. Examples: - NET RX softirq.
From kernel version 3.4.2-2 I get a boot msg like : "NOHZ local_softirq_pending 08" after network start. It causes no problems so far but this message irritates me immensely why print non fatal messages to the screen anyway. This has something to do with my Realtek NIC r8169 (driver=r8169 driverversion=2.3LK-NAPI) and this kernel version May 29, 2017 · RHEL-6.3 Below errors in VM console: "NOHZ: local_softirq_pending 100' was logged." Red Hat Enterprise Linux 6 Issue Kernel logs a message 'NOHZ: local_softirq_pending 100' A system shows a message about 'local_softirq_pending 100' in the system logs. Resolution This is an informal message for debugging, not necessarily a bug.