e43852d149
* Thu Oct 13 2022 Arjun Shankar <arjun@redhat.com> - 2.34-48 - Handle non-hostname CNAME aliases during name resolution (#2129005) - Sync with upstream branch release/2.34/master, commit e3976287b22422787f3cc6fc9adda58304b55bd9: - nscd: Drop local address tuple variable [BZ #29607] - x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations - x86-64: Require BMI2 and LZCNT for AVX2 memrchr implementation - x86-64: Require BMI2 for AVX2 (raw|w)memchr implementations - x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations - x86-64: Require BMI2 for AVX2 strncmp implementation - x86-64: Require BMI2 for AVX2 strcmp implementation - x86-64: Require BMI2 for AVX2 str(n)casecmp implementations - x86: include BMI1 and BMI2 in x86-64-v3 level - nptl: Add backoff mechanism to spinlock loop - sysdeps: Add 'get_fast_jitter' interace in fast-jitter.h - nptl: Effectively skip CAS in spinlock loop - Move assignment out of the CAS condition - Add LLL_MUTEX_READ_LOCK [BZ #28537] - Avoid extra load with CAS in __pthread_mutex_clocklock_common [BZ #28537] - Avoid extra load with CAS in __pthread_mutex_lock_full [BZ #28537] - resolv: Fix building tst-resolv-invalid-cname for earlier C standards - nss_dns: Rewrite _nss_dns_gethostbyname4_r using current interfaces - resolv: Add new tst-resolv-invalid-cname - nss_dns: In gaih_getanswer_slice, skip strange aliases (bug 12154) (#2129005) - nss_dns: Rewrite getanswer_r to match getanswer_ptr (bug 12154, bug 29305) - nss_dns: Remove remnants of IPv6 address mapping - nss_dns: Rewrite _nss_dns_gethostbyaddr2_r and getanswer_ptr - nss_dns: Split getanswer_ptr from getanswer_r - resolv: Add DNS packet parsing helpers geared towards wire format - resolv: Add internal __ns_name_length_uncompressed function - resolv: Add the __ns_samebinaryname function - resolv: Add internal __res_binary_hnok function - resolv: Add tst-resolv-aliases - resolv: Add tst-resolv-byaddr for testing reverse lookup - gconv: Use 64-bit interfaces in gconv_parseconfdir (bug 29583) - elf: Fix hwcaps string size overestimation - nscd: Fix netlink cache invalidation if epoll is used [BZ #29415] - Apply asm redirections in wchar.h before first use - Apply asm redirections in stdio.h before first use [BZ #27087] - elf: Call __libc_early_init for reused namespaces (bug 29528) Resolves: #2129005 Resolves: #2116960
47 lines
1.6 KiB
Diff
47 lines
1.6 KiB
Diff
commit a6b81f605dfba8650ea1f80122f41eb8e6c73dc7
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Author: H.J. Lu <hjl.tools@gmail.com>
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Date: Tue Nov 2 18:33:07 2021 -0700
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Add LLL_MUTEX_READ_LOCK [BZ #28537]
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CAS instruction is expensive. From the x86 CPU's point of view, getting
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a cache line for writing is more expensive than reading. See Appendix
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A.2 Spinlock in:
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https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/xeon-lock-scaling-analysis-paper.pdf
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The full compare and swap will grab the cache line exclusive and cause
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excessive cache line bouncing.
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Add LLL_MUTEX_READ_LOCK to do an atomic load and skip CAS in spinlock
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loop if compare may fail to reduce cache line bouncing on contended locks.
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Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
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(cherry picked from commit d672a98a1af106bd68deb15576710cd61363f7a6)
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diff --git a/nptl/pthread_mutex_lock.c b/nptl/pthread_mutex_lock.c
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index a04e0158451c8fff..9f40928cc6b9a067 100644
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--- a/nptl/pthread_mutex_lock.c
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+++ b/nptl/pthread_mutex_lock.c
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@@ -65,6 +65,11 @@ lll_mutex_lock_optimized (pthread_mutex_t *mutex)
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# define PTHREAD_MUTEX_VERSIONS 1
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#endif
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+#ifndef LLL_MUTEX_READ_LOCK
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+# define LLL_MUTEX_READ_LOCK(mutex) \
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+ atomic_load_relaxed (&(mutex)->__data.__lock)
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+#endif
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+
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static int __pthread_mutex_lock_full (pthread_mutex_t *mutex)
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__attribute_noinline__;
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@@ -142,6 +147,8 @@ PTHREAD_MUTEX_LOCK (pthread_mutex_t *mutex)
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break;
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}
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atomic_spin_nop ();
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+ if (LLL_MUTEX_READ_LOCK (mutex) != 0)
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+ continue;
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}
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while (LLL_MUTEX_TRYLOCK (mutex) != 0);
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