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Re: [PATCH] tunables: Add IFUNC selection and cache sizes
On Wednesday 21 June 2017 10:18 PM, H.J. Lu wrote:
> Oops. Here is the right one.
>
> Sorry for that.
>
>
> 0001-x86-Rename-glibc.tune.ifunc-to-glibc.tune.hwcaps.patch
Looks good.
Thanks,
Siddhesh
> From e5a2f128a7ce24daa377c6888b4940ae7cb7efd0 Mon Sep 17 00:00:00 2001
> From: "H.J. Lu" <hjl.tools@gmail.com>
> Date: Wed, 21 Jun 2017 05:38:03 -0700
> Subject: [PATCH] x86: Rename glibc.tune.ifunc to glibc.tune.hwcaps
>
> Rename glibc.tune.ifunc to glibc.tune.hwcaps and move it to
> sysdeps/x86/dl-tunables.list since it is x86 specicifc. Also
> change type of data_cache_size, data_cache_size and
> non_temporal_threshold to unsigned long int to match size_t.
> Remove usage DEFAULT_STRLEN from cpu-tunables.c.
>
> * elf/dl-tunables.list (glibc.tune.ifunc): Removed.
> * sysdeps/x86/dl-tunables.list (glibc.tune.hwcaps): New.
> Remove security_level on all fields.
> * manual/tunables.texi: Replace ifunc with hwcaps.
> * sysdeps/x86/cpu-features.c (TUNABLE_CALLBACK (set_ifunc)):
> Renamed to ..
> (TUNABLE_CALLBACK (set_hwcaps)): This.
> (init_cpu_features): Updated.
> * sysdeps/x86/cpu-features.h (cpu_features): Change type of
> data_cache_size, data_cache_size and non_temporal_threshold to
> unsigned long int.
> * sysdeps/x86/cpu-tunables.c (DEFAULT_STRLEN): Removed.
> (TUNABLE_CALLBACK (set_ifunc)): Renamed to ...
> (TUNABLE_CALLBACK (set_hwcaps)): This. Update comments. Don't
> use DEFAULT_STRLEN.
> ---
> elf/dl-tunables.list | 4 ----
> manual/tunables.texi | 8 ++++----
> sysdeps/x86/cpu-features.c | 4 ++--
> sysdeps/x86/cpu-features.h | 6 +++---
> sysdeps/x86/cpu-tunables.c | 29 +++++++++++------------------
> sysdeps/x86/dl-tunables.list | 6 +++---
> 6 files changed, 23 insertions(+), 34 deletions(-)
>
> diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
> index b8b0ce5..df4f962 100644
> --- a/elf/dl-tunables.list
> +++ b/elf/dl-tunables.list
> @@ -83,9 +83,5 @@ glibc {
> env_alias: LD_HWCAP_MASK
> default: HWCAP_IMPORTANT
> }
> - ifunc {
> - type: STRING
> - security_level: SXID_IGNORE
> - }
> }
> }
> diff --git a/manual/tunables.texi b/manual/tunables.texi
> index 3263f94..689e894 100644
> --- a/manual/tunables.texi
> +++ b/manual/tunables.texi
> @@ -198,8 +198,8 @@ is 8 times the number of cores online.
> @cindex hardware capability tunables
> @cindex hwcap tunables
> @cindex tunables, hwcap
> -@cindex ifunc tunables
> -@cindex tunables, ifunc
> +@cindex hwcaps tunables
> +@cindex tunables, hwcaps
> @cindex data_cache_size tunables
> @cindex tunables, data_cache_size
> @cindex shared_cache_size tunables
> @@ -222,8 +222,8 @@ extensions available in the processor at runtime for some architectures. The
> capabilities at runtime, thus disabling use of those extensions.
> @end deftp
>
> -@deftp Tunable glibc.tune.ifunc
> -The @code{glibc.tune.ifunc=-xxx,yyy,-zzz...} tunable allows the user to
> +@deftp Tunable glibc.tune.hwcaps
> +The @code{glibc.tune.hwcaps=-xxx,yyy,-zzz...} tunable allows the user to
> enable CPU/ARCH feature @code{yyy}, disable CPU/ARCH feature @code{xxx}
> and @code{zzz} where the feature name is case-sensitive and has to match
> the ones in @code{sysdeps/x86/cpu-features.h}.
> diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> index 76f053a..1d087ea 100644
> --- a/sysdeps/x86/cpu-features.c
> +++ b/sysdeps/x86/cpu-features.c
> @@ -25,7 +25,7 @@
> # include <unistd.h> /* Get STDOUT_FILENO for _dl_printf. */
> # include <elf/dl-tunables.h>
>
> -extern void TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *)
> +extern void TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *)
> attribute_hidden;
> #endif
>
> @@ -322,7 +322,7 @@ no_cpuid:
> cpu_features->kind = kind;
>
> #if HAVE_TUNABLES
> - TUNABLE_GET (ifunc, tunable_val_t *, TUNABLE_CALLBACK (set_ifunc));
> + TUNABLE_GET (hwcaps, tunable_val_t *, TUNABLE_CALLBACK (set_hwcaps));
> cpu_features->non_temporal_threshold
> = TUNABLE_GET (x86_non_temporal_threshold, long int, NULL);
> cpu_features->data_cache_size
> diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
> index fef5e18..3ed67f5 100644
> --- a/sysdeps/x86/cpu-features.h
> +++ b/sysdeps/x86/cpu-features.h
> @@ -217,12 +217,12 @@ struct cpu_features
> unsigned int feature[FEATURE_INDEX_MAX];
> /* Data cache size for use in memory and string routines, typically
> L1 size. */
> - long int data_cache_size;
> + unsigned long int data_cache_size;
> /* Shared cache size for use in memory and string routines, typically
> L2 or L3 size. */
> - long int shared_cache_size;
> + unsigned long int shared_cache_size;
> /* Threshold to use non temporal store. */
> - long int non_temporal_threshold;
> + unsigned long int non_temporal_threshold;
> };
>
> /* Used from outside of glibc to get access to the CPU features
> diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
> index 9258fb4..872dd12 100644
> --- a/sysdeps/x86/cpu-tunables.c
> +++ b/sysdeps/x86/cpu-tunables.c
> @@ -31,16 +31,12 @@
> # if defined USE_MULTIARCH && !defined SHARED
> # ifdef __x86_64__
> # define DEFAULT_MEMCMP __memcmp_sse2
> -# define DEFAULT_STRLEN __strlen_sse2
> # else
> # define DEFAULT_MEMCMP __memcmp_ia32
> -# define DEFAULT_STRLEN strlen
> # endif
> extern __typeof (memcmp) DEFAULT_MEMCMP;
> -extern __typeof (strlen) DEFAULT_STRLEN;
> # else
> # define DEFAULT_MEMCMP memcmp
> -# define DEFAULT_STRLEN strlen
> # endif
>
> # define CHECK_GLIBC_IFUNC_CPU_OFF(f, cpu_features, name, len) \
> @@ -112,30 +108,27 @@ extern __typeof (strlen) DEFAULT_STRLEN;
>
> attribute_hidden
> void
> -TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *valp)
> +TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
> {
> /* The current IFUNC selection is based on microbenchmarks in glibc.
> It should give the best performance for most workloads. But other
> choices may have better performance for a particular workload or on
> the hardware which wasn't available when the selection was made.
> - The environment variable, GLIBC_IFUNC=-xxx,yyy,-zzz...., can be
> - used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature yyy
> - and zzz, where the feature name is case-sensitive and has to match
> - the ones in cpu-features.h. It can be used by glibc developers to
> - tune for a new processor or override the IFUNC selection to improve
> - performance for a particular workload.
> + The environment variable:
>
> - Since all CPU/ARCH features are hardware optimizations without
> - security implication, except for Prefer_MAP_32BIT_EXEC, which can
> - only be disabled, we check GLIBC_IFUNC for programs, including
> - set*id ones.
> + GLIBC_TUNABLES=glibc.tune.hwcaps=-xxx,yyy,-zzz,....
> +
> + can be used to enable CPU/ARCH feature yyy, disable CPU/ARCH feature
> + yyy and zzz, where the feature name is case-sensitive and has to
> + match the ones in cpu-features.h. It can be used by glibc developers
> + to tune for a new processor or override the IFUNC selection to
> + improve performance for a particular workload.
>
> NOTE: the IFUNC selection may change over time. Please check all
> multiarch implementations when experimenting. */
>
> const char *p = valp->strval;
> struct cpu_features *cpu_features = &GLRO(dl_x86_cpu_features);
> - const char *end = p + DEFAULT_STRLEN (p);
> size_t len;
>
> do
> @@ -145,7 +138,7 @@ TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *valp)
> size_t nl;
>
> for (c = p; *c != ','; c++)
> - if (c >= end)
> + if (*c == '\0')
> break;
>
> len = c - p;
> @@ -325,6 +318,6 @@ TUNABLE_CALLBACK (set_ifunc) (tunable_val_t *valp)
> }
> p += len + 1;
> }
> - while (p < end);
> + while (*p != '\0');
> }
> #endif
> diff --git a/sysdeps/x86/dl-tunables.list b/sysdeps/x86/dl-tunables.list
> index 50c130a..99a9cc4 100644
> --- a/sysdeps/x86/dl-tunables.list
> +++ b/sysdeps/x86/dl-tunables.list
> @@ -18,17 +18,17 @@
>
> glibc {
> tune {
> + hwcaps {
> + type: STRING
> + }
> x86_non_temporal_threshold {
> type: SIZE_T
> - security_level: SXID_IGNORE
> }
> x86_data_cache_size {
> type: SIZE_T
> - security_level: SXID_IGNORE
> }
> x86_shared_cache_size {
> type: SIZE_T
> - security_level: SXID_IGNORE
> }
> }
> }
>