而决定这个布尔值的是我们调用的是static_branch_likely!还是static_branch_unlikely!,以及static key的初始值。 当我们修改static branch时,我们可以通过将static key的新值与jump entry中记录的初始状态异或得到。例如,如果更有可能执行到的分支是true分支,并且static key的新值是true,那么我们应当将jmp更新为nop。这...
if(static_branch_unlikely(&key)) 执行不太可能的代码 else 执行可能的代码 或者: if(static_branch_likely(&key)) 执行可能的代码 else 执行不太可能的代码 通过DEFINE_STATIC_KEY_TRUE()或DEFINE_STATIC_KEY_FALSE定义的键可以在static_branch_likely()或static_branch_unlikely()语句中使用。 可以通过以下方式...
static_branch_likely和static_branch_unlikely主要是调用arch_static_branch和arch_static_branch_jump来判断。 arch_static_branch表示条件成立,继续执行 例如: if(static_branch_likely(&sched_numa_balancing))return; 就直接return了 而arch_static_branch_jump表示条件不成立,执行跳转。 使用这种机制比likely和unlikel...
fn run() { loop { if static_branch_unlikely!(FLAG_STATIC_KEY) { do_something(); } do_common_routines(); } } 参考链接 Linux内核官方文档:static-keys f="terenceli.github.io/%E6">Linux static_key internals Rust for Linux项目也实现了static key,请查看Rust-for-Linux/linux#1084。我们基于...
static_branch_unlikely()分支将以对可能代码路径的最小影响生成到代码中。 动机 目前,跟踪点是使用条件分支实现的。条件检查需要为每个跟踪点检查一个全局变量。尽管此检查的开销很小,但当内存缓存承受压力时(这些全局变量的内存缓存行可能与其他内存访问共享),开销会增加。随着内核中跟踪点数量的增加,这种开销可能变得...
if(static_branch_unlikely(&deferred_pages)){ if(_deferred_grow_zone(zone,order)) gototry_this_zone; } #endif } } returnNULL; } 这段代码实现了从空闲列表中获取页面的函数。以下是对关键部分的注释: z:指向首选区域引用的指针。 for_next_zone_zonelist_nodemask:遍历备用区域列表中满足条件的区域。
Oh! In my use case, I found that using static_branch_unlikely(&memcg_kmem_enabled_key) -> unlikely(&(&memcg_kmem_enabled_key)->key) works well. It may be a use case of fixing static key. To adjust to the patch-author-guide, I have add an new case using static_key_enabled while...
(static_branch_unlikely(&key)) do unlikely code else do likely code Or:: if (static_branch_likely(&key)) do likely code else do unlikely code Keys defined via DEFINE_STATIC_KEY_TRUE(), or DEFINE_STATIC_KEY_FALSE, may be used in either static_branch_likely() or static...
+ if (unlikely(val == KVM_ARM_PSCI_0_1)) + val = PSCI_RET_NOT_SUPPORTED; + vcpu_set_reg(vcpu, 0, val); + goto again; + } } if (static_branch_unlikely(&vgic_v2_cpuif_trap) && diff --git a/include/kvm/arm_psci.h b/include/kvm/arm_psci.h ...
In the beginning I had the variable as a member but then I needed to branch off and so I made it local without static for the time being just to test things out as I continue to change code. I just tried to make it static local in the function and no good. I don't get it as...