Mostly use cfg!() rather than #[cfg] for controlling sys_stat

This only adds 48 bytes overhead per cpu core in the PerCpuBlock struct.
Also fixes compilation with sys_stat enabled on x86_64.

src/context/context.rs

@@ -8,13 +8,12 @@ use core::{
 use spin::RwLock;
 use syscall::{SigProcControl, Sigcontrol, UPPER_FDTBL_TAG};
 
-#[cfg(feature = "sys_stat")]
-use crate::cpu_stats;
 use crate::{
     arch::{interrupt::InterruptStack, paging::PAGE_SIZE},
     common::aligned_box::AlignedBox,
     context::{self, arch, file::FileDescriptor},
     cpu_set::{LogicalCpuId, LogicalCpuSet},
+    cpu_stats,
     ipi::{ipi, IpiKind, IpiTarget},
     memory::{allocate_p2frame, deallocate_p2frame, Enomem, Frame, RaiiFrame},
     paging::{RmmA, RmmArch},
@@ -190,7 +189,6 @@ impl Context {
             #[cfg(feature = "syscall_debug")]
             syscall_debug_info: crate::syscall::debug::SyscallDebugInfo::default(),
         };
-        #[cfg(feature = "sys_stat")]
         cpu_stats::add_context();
         Ok(this)
     }

src/context/switch.rs

@@ -15,14 +15,11 @@ use syscall::PtraceFlags;
 use crate::{
     context::{arch, contexts, Context},
     cpu_set::LogicalCpuId,
-    interrupt,
+    cpu_stats, interrupt,
     percpu::PercpuBlock,
     ptrace, time,
 };
 
-#[cfg(feature = "sys_stat")]
-use crate::cpu_stats;
-
 use super::ContextRef;
 
 enum UpdateResult {
@@ -141,13 +138,10 @@ pub enum SwitchResult {
 ///   to an idle context.
 pub fn switch() -> SwitchResult {
     let percpu = PercpuBlock::current();
-    #[cfg(feature = "sys_stat")]
-    {
-        cpu_stats::add_context_switch();
-        percpu
-            .stats
-            .add_time(percpu.switch_internals.pit_ticks.get());
-    }
+    cpu_stats::add_context_switch();
+    percpu
+        .stats
+        .add_time(percpu.switch_internals.pit_ticks.get());
 
     //set PIT Interrupt counter to 0, giving each process same amount of PIT ticks
     percpu.switch_internals.pit_ticks.set(0);
@@ -292,13 +286,10 @@ pub fn switch() -> SwitchResult {
         // need to use the `switch_finish_hook` to be able to release the locks. Newly created
         // contexts will return directly to the function pointer passed to context::spawn, and not
         // reach this code until the next context switch back.
-        #[cfg(feature = "sys_stat")]
-        {
-            if next_context.userspace {
-                percpu.stats.set_state(cpu_stats::CpuState::User);
-            } else {
-                percpu.stats.set_state(cpu_stats::CpuState::Kernel);
-            }
+        if next_context.userspace {
+            percpu.stats.set_state(cpu_stats::CpuState::User);
+        } else {
+            percpu.stats.set_state(cpu_stats::CpuState::Kernel);
         }
 
         SwitchResult::Switched
@@ -306,10 +297,7 @@ pub fn switch() -> SwitchResult {
         // No target was found, unset global lock and return
         arch::CONTEXT_SWITCH_LOCK.store(false, Ordering::SeqCst);
 
-        #[cfg(feature = "sys_stat")]
-        {
-            percpu.stats.set_state(cpu_stats::CpuState::Idle);
-        }
+        percpu.stats.set_state(cpu_stats::CpuState::Idle);
 
         SwitchResult::AllContextsIdle
     }