193 lines
6.0 KiB
Diff
193 lines
6.0 KiB
Diff
commit cb89ba9c72f66327f5d66034681eb1d46eedf96f
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Author: DJ Delorie <dj@redhat.com>
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Date: Thu Aug 8 19:09:43 2019 -0400
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Add glibc.malloc.mxfast tunable
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* elf/dl-tunables.list: Add glibc.malloc.mxfast.
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* manual/tunables.texi: Document it.
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* malloc/malloc.c (do_set_mxfast): New.
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(__libc_mallopt): Call it.
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* malloc/arena.c: Add mxfast tunable.
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* malloc/tst-mxfast.c: New.
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* malloc/Makefile: Add it.
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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(cherry picked from commit c48d92b430c480de06762f80c104922239416826)
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diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
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index 1f8ecb8437a0460f..1ff6fcb6f24f93a8 100644
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--- a/elf/dl-tunables.list
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+++ b/elf/dl-tunables.list
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@@ -85,6 +85,11 @@ glibc {
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tcache_unsorted_limit {
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type: SIZE_T
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}
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+ mxfast {
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+ type: SIZE_T
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+ minval: 0
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+ security_level: SXID_IGNORE
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+ }
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}
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tune {
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hwcap_mask {
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diff --git a/malloc/Makefile b/malloc/Makefile
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index 228a1279a5960d8c..bf9a53cb7c5ebacb 100644
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--- a/malloc/Makefile
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+++ b/malloc/Makefile
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@@ -39,6 +39,7 @@ tests := mallocbug tst-malloc tst-valloc tst-calloc tst-obstack \
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tst-malloc-too-large \
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tst-malloc-stats-cancellation \
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tst-tcfree1 tst-tcfree2 tst-tcfree3 \
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+ tst-mxfast \
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tests-static := \
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tst-interpose-static-nothread \
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@@ -196,6 +197,8 @@ tst-malloc-usable-static-ENV = $(tst-malloc-usable-ENV)
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tst-malloc-usable-tunables-ENV = GLIBC_TUNABLES=glibc.malloc.check=3
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tst-malloc-usable-static-tunables-ENV = $(tst-malloc-usable-tunables-ENV)
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+tst-mxfast-ENV = GLIBC_TUNABLES=glibc.malloc.tcache_count=0:glibc.malloc.mxfast=0
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+
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ifeq ($(experimental-malloc),yes)
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CPPFLAGS-malloc.c += -DUSE_TCACHE=1
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else
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diff --git a/malloc/arena.c b/malloc/arena.c
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index ff8fd5d2a7e51ac8..f5c7ad4570ad6186 100644
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--- a/malloc/arena.c
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+++ b/malloc/arena.c
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@@ -237,6 +237,7 @@ TUNABLE_CALLBACK_FNDECL (set_tcache_max, size_t)
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TUNABLE_CALLBACK_FNDECL (set_tcache_count, size_t)
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TUNABLE_CALLBACK_FNDECL (set_tcache_unsorted_limit, size_t)
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#endif
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+TUNABLE_CALLBACK_FNDECL (set_mxfast, size_t)
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#else
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/* Initialization routine. */
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#include <string.h>
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@@ -324,6 +325,7 @@ ptmalloc_init (void)
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TUNABLE_GET (tcache_unsorted_limit, size_t,
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TUNABLE_CALLBACK (set_tcache_unsorted_limit));
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# endif
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+ TUNABLE_GET (mxfast, size_t, TUNABLE_CALLBACK (set_mxfast));
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#else
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const char *s = NULL;
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if (__glibc_likely (_environ != NULL))
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diff --git a/malloc/malloc.c b/malloc/malloc.c
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index fcf480acdaea1b86..9756ed0a0d28c5f6 100644
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--- a/malloc/malloc.c
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+++ b/malloc/malloc.c
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@@ -5142,6 +5142,19 @@ do_set_tcache_unsorted_limit (size_t value)
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}
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#endif
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+static inline int
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+__always_inline
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+do_set_mxfast (size_t value)
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+{
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+ if (value >= 0 && value <= MAX_FAST_SIZE)
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+ {
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+ LIBC_PROBE (memory_mallopt_mxfast, 2, value, get_max_fast ());
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+ set_max_fast (value);
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+ return 1;
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+ }
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+ return 0;
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+}
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+
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int
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__libc_mallopt (int param_number, int value)
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{
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@@ -5161,13 +5174,7 @@ __libc_mallopt (int param_number, int value)
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switch (param_number)
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{
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case M_MXFAST:
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- if (value >= 0 && value <= MAX_FAST_SIZE)
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- {
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- LIBC_PROBE (memory_mallopt_mxfast, 2, value, get_max_fast ());
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- set_max_fast (value);
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- }
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- else
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- res = 0;
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+ do_set_mxfast (value);
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break;
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case M_TRIM_THRESHOLD:
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diff --git a/malloc/tst-mxfast.c b/malloc/tst-mxfast.c
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new file mode 100644
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index 0000000000000000..7a371d2f9d2f0005
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--- /dev/null
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+++ b/malloc/tst-mxfast.c
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@@ -0,0 +1,50 @@
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+/* Test that glibc.malloc.mxfast tunable works.
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+ Copyright (C) 2018, 2019 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <http://www.gnu.org/licenses/>. */
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+
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+/* This test verifies that setting the glibc.malloc.mxfast tunable to
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+ zero results in free'd blocks being returned to the small bins, not
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+ the fast bins. */
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+
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+#include <malloc.h>
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+#include <assert.h>
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+
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+int
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+do_test(void)
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+{
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+ struct mallinfo m;
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+ char * volatile p1;
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+ char * volatile p2;
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+
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+ /* Arbitrary value; must be in default fastbin range. */
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+ p1 = malloc (3);
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+ /* Something large so that p1 isn't a "top block" */
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+ p2 = malloc (512);
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+ free (p1);
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+
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+ m = mallinfo();
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+
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+ /* This will fail if there are any blocks in the fastbins. */
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+ assert (m.smblks == 0);
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+
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+ /* To keep gcc happy. */
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+ free (p2);
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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diff --git a/manual/tunables.texi b/manual/tunables.texi
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index f6c49250e3889ddd..3dc6f9a44592c030 100644
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--- a/manual/tunables.texi
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+++ b/manual/tunables.texi
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@@ -213,6 +213,18 @@ pre-fill the per-thread cache with. The default, or when set to zero,
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is no limit.
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@end deftp
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+@deftp Tunable glibc.malloc.mxfast
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+One of the optimizations malloc uses is to maintain a series of ``fast
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+bins'' that hold chunks up to a specific size. The default and
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+maximum size which may be held this way is 80 bytes on 32-bit systems
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+or 160 bytes on 64-bit systems. Applications which value size over
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+speed may choose to reduce the size of requests which are serviced
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+from fast bins with this tunable. Note that the value specified
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+includes malloc's internal overhead, which is normally the size of one
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+pointer, so add 4 on 32-bit systems or 8 on 64-bit systems to the size
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+passed to @code{malloc} for the largest bin size to enable.
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+@end deftp
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+
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@node Elision Tunables
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@section Elision Tunables
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@cindex elision tunables
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