From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org
Cc: "H . J . Lu" <hjl.tools@gmail.com>,
Noah Goldstein <goldstein.w.n@gmail.com>,
Sajan Karumanchi <sajan.karumanchi@gmail.com>,
bmerry@sarao.ac.za, pmallapp@amd.com
Subject: [PATCH v2 3/3] x86: Expand the comment on when REP STOSB is used on memset
Date: Tue, 6 Feb 2024 14:43:22 -0300 [thread overview]
Message-ID: <20240206174322.2317679-4-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20240206174322.2317679-1-adhemerval.zanella@linaro.org>
---
sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
index 9984c3ca0f..97839a2248 100644
--- a/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
+++ b/sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
@@ -21,7 +21,9 @@
2. If size is less than VEC, use integer register stores.
3. If size is from VEC_SIZE to 2 * VEC_SIZE, use 2 VEC stores.
4. If size is from 2 * VEC_SIZE to 4 * VEC_SIZE, use 4 VEC stores.
- 5. If size is more to 4 * VEC_SIZE, align to 4 * VEC_SIZE with
+ 5. On machines ERMS feature, if size is greater or equal than
+ __x86_rep_stosb_threshold then REP STOSB will be used.
+ 6. If size is more to 4 * VEC_SIZE, align to 4 * VEC_SIZE with
4 VEC stores and store 4 * VEC at a time until done. */
#include <sysdep.h>
--
2.34.1
prev parent reply other threads:[~2024-02-06 17:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-06 17:43 [PATCH v2 0/3] x86: Improve ERMS usage on Zen3+ Adhemerval Zanella
2024-02-06 17:43 ` [PATCH v2 1/3] x86: Fix Zen3/Zen4 ERMS selection (BZ 30994) Adhemerval Zanella
2024-02-06 18:36 ` Noah Goldstein
2024-02-07 12:10 ` Adhemerval Zanella Netto
2024-02-07 17:39 ` Noah Goldstein
2024-02-07 18:06 ` Adhemerval Zanella Netto
2024-02-07 18:10 ` Adhemerval Zanella Netto
2024-02-07 22:07 ` Noah Goldstein
2024-02-09 10:59 ` Karumanchi, Sajan
2024-02-06 17:43 ` [PATCH v2 2/3] x86: Do not prefer ERMS for memset on Zen3+ Adhemerval Zanella
2024-02-06 19:01 ` Noah Goldstein
2024-02-07 12:14 ` Adhemerval Zanella Netto
2024-02-06 17:43 ` Adhemerval Zanella [this message]
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