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The following commit(s) were added to refs/heads/master by this push:
new 61caf7cce9 types: on some arch, execution speed can be accelerated
61caf7cce9 is described below
commit 61caf7cce90d77840a67353db78cea146c2c8f7b
Author: hujun5 <[email protected]>
AuthorDate: Thu Jan 11 21:34:24 2024 +0800
types: on some arch, execution speed can be accelerated
in arm64 Let's see how the following code looks like in assembly
volatile cpu_set_t g_cpu_set;
cpu_set_t set_cpu_set_t_set(int cpu) {
g_cpu_set &= ~(1 << cpu);
return g_cpu_set;
}
when
typedef volatile uint32_t cpu_set_t;
Dump of assembler code for function set_cpu_set_t_set:
0x0000000040288570 <+0>: adrp x2, 0x403ce000 <g_irqvector+1160>
0x0000000040288574 <+4>: ldr w3, [x2, #2368]
0x0000000040288578 <+8>: mov w1, #0x1
0x000000004028857c <+12>: lsl w1, w1, w0
0x0000000040288580 <+16>: bic w1, w3, w1
0x0000000040288584 <+20>: str w1, [x2, #2368]
0x0000000040288588 <+24>: ldr w0, [x2, #2368]
0x000000004028858c <+28>: ret
when
typedef volatile uint8_t cpu_set_t;
Dump of assembler code for function set_cpu_set_t_set:
0x000000004028856c <+0>: adrp x2, 0x403ce000 <g_irqvector+1192>
0x0000000040288570 <+4>: ldrb w3, [x2, #2336]
0x0000000040288574 <+8>: mov w1, #0x1
0x0000000040288578 <+12>: and w3, w3, #0xff // At this
time, there will be one more instruction
0x000000004028857c <+16>: lsl w1, w1, w0
0x0000000040288580 <+20>: bic w1, w3, w1
0x0000000040288584 <+24>: strb w1, [x2, #2336]
0x0000000040288588 <+28>: ldrb w0, [x2, #2336]
0x000000004028858c <+32>: ret
test:
We can use qemu for testing.
compiling
make distclean -j20; ./tools/configure.sh -l qemu-armv8a:nsh_smp ;make -j20
running
qemu-system-aarch64 -cpu cortex-a53 -smp 4 -nographic -machine
virt,virtualization=on,gic-version=3 -net none -chardev stdio,id=con,mux=on
-serial chardev:con -mon chardev=con,mode=readline -kernel ./nuttx
Signed-off-by: hujun5 <[email protected]>
---
include/sys/types.h | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/include/sys/types.h b/include/sys/types.h
index d19448d0d2..a87827b5f1 100644
--- a/include/sys/types.h
+++ b/include/sys/types.h
@@ -268,11 +268,7 @@ typedef int32_t suseconds_t;
/* This is the smallest integer type that will hold a bitset of all CPUs */
-#if (CONFIG_SMP_NCPUS <= 8)
-typedef volatile uint8_t cpu_set_t;
-#elif (CONFIG_SMP_NCPUS <= 16)
-typedef volatile uint16_t cpu_set_t;
-#elif (CONFIG_SMP_NCPUS <= 32)
+#if (CONFIG_SMP_NCPUS <= 32)
typedef volatile uint32_t cpu_set_t;
#else
# error SMP: Extensions needed to support this number of CPUs
