Messages in this thread | | | From | Christophe Leroy <> | Subject | [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation. | Date | Mon, 13 Jan 2020 17:08:38 +0000 (UTC) |
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This is a third tentative to switch powerpc VDSO to generic C implementation.
This version should work on PPC64 (untested). VDSO32 for PPC64 is impossible to build and has been de-activated, because the powerpc ASM header files for C are not prepared to build 32 bits code with CONFIG_PPC64.
powerpc is a bit special for VDSO as well as system calls in the way that it requires setting CR SO bit which cannot be done in C. Therefore, entry/exit and fallback need to be performed in ASM.
On a powerpc8xx, with current powerpc/32 ASM VDSO:
gettimeofday: vdso: 737 nsec/call clock-getres-realtime: vdso: 475 nsec/call clock-gettime-realtime: vdso: 892 nsec/call
The first patch adds VDSO generic C support without any changes to common code. Performance is as follows:
gettimeofday: vdso: 1379 nsec/call clock-getres-realtime-coarse: vdso: 984 nsec/call clock-gettime-realtime-coarse: vdso: 868 nsec/call clock-getres-realtime: vdso: 922 nsec/call clock-gettime-realtime: vdso: 1511 nsec/call clock-getres-monotonic-raw: vdso: 968 nsec/call clock-gettime-monotonic-raw: vdso: 1576 nsec/call
Then a few changes in the common code have allowed performance improvement. At the end of the series we have:
gettimeofday: vdso: 899 nsec/call clock-getres-realtime-coarse: vdso: 546 nsec/call clock-gettime-realtime-coarse: vdso: 615 nsec/call clock-getres-realtime: vdso: 545 nsec/call clock-gettime-realtime: vdso: 1064 nsec/call clock-getres-monotonic-raw: vdso: 546 nsec/call clock-gettime-monotonic-raw: vdso: 1125 nsec/call
Christophe Leroy (12): powerpc/64: Don't provide time functions in compat VDSO32 powerpc/vdso: Switch VDSO to generic C implementation. lib: vdso: mark __cvdso_clock_getres() as static lib: vdso: inline do_hres() and do_coarse() lib: vdso: Avoid duplication in __cvdso_clock_getres() lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time powerpc/vdso: simplify __get_datapage() lib: vdso: allow arches to provide vdso data pointer powerpc/vdso: provide inline alternative to __get_datapage() powerpc/vdso: provide vdso data pointer from the ASM caller. lib: vdso: split clock verification out of __arch_get_hw_counter() powerpc/vdso: provide __arch_is_hw_counter_valid()
arch/powerpc/Kconfig | 2 + arch/powerpc/include/asm/vdso/gettimeofday.h | 104 +++++++++++ arch/powerpc/include/asm/vdso/vsyscall.h | 25 +++ arch/powerpc/include/asm/vdso_datapage.h | 52 +++--- arch/powerpc/kernel/asm-offsets.c | 46 +---- arch/powerpc/kernel/time.c | 90 ---------- arch/powerpc/kernel/vdso.c | 58 ++---- arch/powerpc/kernel/vdso32/Makefile | 30 +++- arch/powerpc/kernel/vdso32/datapage.S | 10 +- arch/powerpc/kernel/vdso32/gettimeofday.S | 258 ++++----------------------- arch/powerpc/kernel/vdso32/vdso32.lds.S | 9 +- arch/powerpc/kernel/vdso32/vgettimeofday.c | 29 +++ arch/powerpc/kernel/vdso64/Makefile | 23 ++- arch/powerpc/kernel/vdso64/datapage.S | 13 +- arch/powerpc/kernel/vdso64/gettimeofday.S | 257 ++++---------------------- arch/powerpc/kernel/vdso64/vdso64.lds.S | 7 +- arch/powerpc/kernel/vdso64/vgettimeofday.c | 29 +++ lib/vdso/gettimeofday.c | 130 +++++++++++--- 18 files changed, 457 insertions(+), 715 deletions(-) create mode 100644 arch/powerpc/include/asm/vdso/gettimeofday.h create mode 100644 arch/powerpc/include/asm/vdso/vsyscall.h create mode 100644 arch/powerpc/kernel/vdso32/vgettimeofday.c create mode 100644 arch/powerpc/kernel/vdso64/vgettimeofday.c
-- 2.13.3
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