hrev53783 adds 1 changeset to branch 'master'
old head: 97e67e3f6335c647b58ec8a3d67f8dec1d4aa675
new head: 2d697067b2021ca5369f875289415dae30340af2
overview:
https://git.haiku-os.org/haiku/log/?qt=range&q=2d697067b202+%5E97e67e3f6335
----------------------------------------------------------------------------
2d697067b202: Further cleanup/optimization of system_time
On gcc4, we can use the __rdtsc builtin. On gcc2, provide a similar
inline-able version of rdtsc, and remove the rdtsc function written in
assembly, saving a call/ret on every call.
There has been some discussion about performance, but note that this is
only bootloader code, it is not used when the system is up and running,
therefore performance is not that critical.
[ Adrien Destugues <pulkomandy@xxxxxxxxxxxxx> ]
----------------------------------------------------------------------------
Revision: hrev53783
Commit: 2d697067b2021ca5369f875289415dae30340af2
URL: https://git.haiku-os.org/haiku/commit/?id=2d697067b202
Author: Adrien Destugues <pulkomandy@xxxxxxxxxxxxx>
Date: Mon Jan 27 20:46:43 2020 UTC
----------------------------------------------------------------------------
4 files changed, 15 insertions(+), 24 deletions(-)
src/system/boot/arch/x86/cpu.cpp | 19 ++++++++++++++-----
src/system/boot/platform/bios_ia32/debug.cpp | 7 +------
src/system/boot/platform/bios_ia32/support.S | 5 -----
src/system/boot/platform/efi/support.S | 8 --------
----------------------------------------------------------------------------
diff --git a/src/system/boot/arch/x86/cpu.cpp b/src/system/boot/arch/x86/cpu.cpp
index 9389fe042b..91f2ae9337 100644
--- a/src/system/boot/arch/x86/cpu.cpp
+++ b/src/system/boot/arch/x86/cpu.cpp
@@ -23,8 +23,6 @@
#include <string.h>
-extern "C" uint64 rdtsc();
-
uint32 gTimeConversionFactor;
// PIT definitions
@@ -66,6 +64,17 @@ uint32 gTimeConversionFactor;
// TODO: These are arbitrary. They are here to avoid spinning
indefinitely
// if the TSC just isn't stable and we can't get our desired error
range.
+#if __GNUC__ <= 2
+// It's a builtin on later compiler versions, but not in gcc2...
+static inline uint64_t __rdtsc()
+{
+ uint64 tsc;
+
+ asm volatile ("rdtsc\n" : "=A"(tsc));
+
+ return tsc;
+}
+#endif
struct uint128 {
uint128(uint64 low, uint64 high = 0)
@@ -198,7 +207,7 @@ calibration_loop(uint8 desiredHighByte, uint8 channel,
uint64& tscDelta,
} while (startHigh != 255);
// Read in the first TSC value
- uint64 startTSC = rdtsc();
+ uint64 startTSC = __rdtsc();
// Wait for the PIT to count down to our desired value
uint8 endLow;
@@ -210,7 +219,7 @@ calibration_loop(uint8 desiredHighByte, uint8 channel,
uint64& tscDelta,
} while (endHigh > desiredHighByte);
// And read the second TSC value
- uint64 endTSC = rdtsc();
+ uint64 endTSC = __rdtsc();
tscDelta = endTSC - startTSC;
expired = ((startHigh << 8) | startLow) - ((endHigh << 8) | endLow);
@@ -304,7 +313,7 @@ slower_sample:
extern "C" bigtime_t
system_time()
{
- uint64 tsc = rdtsc();
+ uint64 tsc = __rdtsc();
uint64 lo = (uint32)tsc;
uint64 hi = tsc >> 32;
return ((lo * gTimeConversionFactor) >> 32) + hi *
gTimeConversionFactor;
diff --git a/src/system/boot/platform/bios_ia32/debug.cpp
b/src/system/boot/platform/bios_ia32/debug.cpp
index 9bbc6dc708..4fc67738ac 100644
--- a/src/system/boot/platform/bios_ia32/debug.cpp
+++ b/src/system/boot/platform/bios_ia32/debug.cpp
@@ -32,11 +32,6 @@ static ring_buffer* sDebugSyslogBuffer = NULL;
static bool sPostCleanup = false;
-#ifdef PRINT_TIME_STAMPS
-extern "C" uint64 rdtsc();
-#endif
-
-
static void
syslog_write(const char* buffer, size_t length)
{
@@ -65,7 +60,7 @@ dprintf_args(const char *format, va_list args)
if (sNewLine) {
char timeBuffer[32];
- snprintf(timeBuffer, sizeof(timeBuffer), "[%" B_PRIu64 "] ",
rdtsc());
+ snprintf(timeBuffer, sizeof(timeBuffer), "[%" B_PRIu64 "] ",
__rdtsc());
syslog_write(timeBuffer, strlen(timeBuffer));
serial_puts(timeBuffer, strlen(timeBuffer));
}
diff --git a/src/system/boot/platform/bios_ia32/support.S
b/src/system/boot/platform/bios_ia32/support.S
index ce89d6d892..442b72dcb5 100644
--- a/src/system/boot/platform/bios_ia32/support.S
+++ b/src/system/boot/platform/bios_ia32/support.S
@@ -7,11 +7,6 @@
#define FUNCTION(x) .global x; .type x,@function; x
-/* uint64 rdtsc() */
-FUNCTION(rdtsc):
- rdtsc
- ret
-
FUNCTION(execute_n_instructions):
movl 4(%esp), %ecx
shrl $4, %ecx
diff --git a/src/system/boot/platform/efi/support.S
b/src/system/boot/platform/efi/support.S
index 81828472d6..4c77461fae 100644
--- a/src/system/boot/platform/efi/support.S
+++ b/src/system/boot/platform/efi/support.S
@@ -7,14 +7,6 @@
#define FUNCTION(x) .global x; .type x,@function; x
-/* uint64 rdtsc() */
-FUNCTION(rdtsc):
- rdtsc
- /* Convert to 64-bit result in rax. */
- shlq $32, %rdx
- orq %rdx, %rax
- ret
-
FUNCTION(execute_n_instructions):
movl %edi, %ecx
shrl $4, %ecx
