[Refreshed for 2.6.24]
This patch does:
- Remove outdated comments (which someday I marked with "?").
- Reassemble instructions to fit them in fewer bundles.
- If McKinley Errata 9 workaround is not needed, the workaround
bundles will be patched out with NOPs. However it also not
needed to have a totally NOP bundle (nop * 3) before branch.
As a result, this makes the code path 3 (or 2) bundles shorter
(and remove 1 unnecessary stop bit). It seems to be 1% faster.
(10sec loop test, with nojitter @ Madison 1.5GHz x 4)
Before:
CPU 0: 0.14 (usecs) (0 errors / 69598875 iterations)
CPU 1: 0.14 (usecs) (0 errors / 69630721 iterations)
CPU 2: 0.14 (usecs) (0 errors / 69607850 iterations)
CPU 3: 0.14 (usecs) (0 errors / 69619832 iterations)
After:
CPU 0: 0.14 (usecs) (0 errors / 70257728 iterations)
CPU 1: 0.14 (usecs) (0 errors / 70309498 iterations)
CPU 2: 0.14 (usecs) (0 errors / 70280639 iterations)
CPU 3: 0.14 (usecs) (0 errors / 70260682 iterations)
Signed-off-by: Hidetoshi Seto <seto.hidetoshi@xxxxxxxxxxxxxx>
---
arch/ia64/kernel/fsys.S | 28 ++++++++++++----------------
arch/ia64/kernel/patch.c | 8 ++++----
2 files changed, 16 insertions(+), 20 deletions(-)
Index: linux-2.6.24/arch/ia64/kernel/fsys.S
===================================================================
--- linux-2.6.24.orig/arch/ia64/kernel/fsys.S
+++ linux-2.6.24/arch/ia64/kernel/fsys.S
@@ -210,27 +210,25 @@
// Note that instructions are optimized for McKinley. McKinley can
// process two bundles simultaneously and therefore we continuously
// try to feed the CPU two bundles and then a stop.
- //
- // Additional note that code has changed a lot. Optimization is TBD.
- // Comments begin with "?" are maybe outdated.
- tnat.nz p6,p0 = r31 // ? branch deferred to fit later bundle
- mov pr = r30,0xc000 // Set predicates according to function
+
add r2 = TI_FLAGS+IA64_TASK_SIZE,r16
+ tnat.nz p6,p0 = r31 // guard against Nat argument
+(p6) br.cond.spnt.few .fail_einval
movl r20 = fsyscall_gtod_data // load fsyscall gettimeofday data address
;;
+ ld4 r2 = [r2] // process work pending flags
movl r29 = itc_jitter_data // itc_jitter
add r22 = IA64_GTOD_WALL_TIME_OFFSET,r20 // wall_time
- ld4 r2 = [r2] // process work pending flags
- ;;
-(p15) add r22 = IA64_GTOD_MONO_TIME_OFFSET,r20 // monotonic_time
add r21 = IA64_CLKSRC_MMIO_OFFSET,r20
- add r19 = IA64_ITC_LASTCYCLE_OFFSET,r29
+ mov pr = r30,0xc000 // Set predicates according to function
+ ;;
and r2 = TIF_ALLWORK_MASK,r2
-(p6) br.cond.spnt.few .fail_einval // ? deferred branch
+ add r19 = IA64_ITC_LASTCYCLE_OFFSET,r29
+(p15) add r22 = IA64_GTOD_MONO_TIME_OFFSET,r20 // monotonic_time
;;
- add r26 = IA64_CLKSRC_CYCLE_LAST_OFFSET,r20 // clksrc_cycle_last
+ add r26 = IA64_CLKSRC_CYCLE_LAST_OFFSET,r20 // clksrc_cycle_last
cmp.ne p6, p0 = 0, r2 // Fallback if work is scheduled
-(p6) br.cond.spnt.many fsys_fallback_syscall
+(p6) br.cond.spnt.many fsys_fallback_syscall
;;
// Begin critical section
.time_redo:
@@ -258,7 +256,6 @@
(p8) mov r2 = ar.itc // CPU_TIMER. 36 clocks latency!!!
(p9) ld8 r2 = [r30] // MMIO_TIMER. Could also have latency issues..
(p13) ld8 r25 = [r19] // get itc_lastcycle value
- ;; // ? could be removed by moving the last add upward
ld8 r9 = [r22],IA64_TIMESPEC_TV_NSEC_OFFSET // tv_sec
;;
ld8 r8 = [r22],-IA64_TIMESPEC_TV_NSEC_OFFSET // tv_nsec
@@ -285,13 +282,12 @@
EX(.fail_efault, probe.w.fault r31, 3)
xmpy.l f8 = f8,f7 // nsec_per_cyc*(counter-last_counter)
;;
- // ? simulate tbit.nz.or p7,p0 = r28,0
getf.sig r2 = f8
mf
;;
ld4 r10 = [r20] // gtod_lock.sequence
shr.u r2 = r2,r23 // shift by factor
- ;; // ? overloaded 3 bundles!
+ ;;
add r8 = r8,r2 // Add xtime.nsecs
cmp4.ne p7,p0 = r28,r10
(p7) br.cond.dpnt.few .time_redo // sequence number changed, redo
@@ -319,9 +315,9 @@
EX(.fail_efault, probe.w.fault r23, 3) // This also costs 5 cycles
(p14) xmpy.hu f8 = f8, f7 // xmpy has 5 cycles latency so use it
;;
- mov r8 = r0
(p14) getf.sig r2 = f8
;;
+ mov r8 = r0
(p14) shr.u r21 = r2, 4
;;
EX(.fail_efault, st8 [r31] = r9)
Index: linux-2.6.24/arch/ia64/kernel/patch.c
===================================================================
--- linux-2.6.24.orig/arch/ia64/kernel/patch.c
+++ linux-2.6.24/arch/ia64/kernel/patch.c
@@ -135,10 +135,10 @@
while (offp < (s32 *) end) {
wp = (u64 *) ia64_imva((char *) offp + *offp);
- wp[0] = 0x0000000100000000UL; /* nop.m 0; nop.i 0; nop.i 0 */
- wp[1] = 0x0004000000000200UL;
- wp[2] = 0x0000000100000011UL; /* nop.m 0; nop.i 0; br.ret.sptk.many b6 */
- wp[3] = 0x0084006880000200UL;
+ wp[0] = 0x0000000100000011UL; /* nop.m 0; nop.i 0; br.ret.sptk.many b6 */
+ wp[1] = 0x0084006880000200UL;
+ wp[2] = 0x0000000100000000UL; /* nop.m 0; nop.i 0; nop.i 0 */
+ wp[3] = 0x0004000000000200UL;
ia64_fc(wp); ia64_fc(wp + 2);
++offp;
}
-
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