From: Alexander Monakov <amonakov@ispras.ru>
To: Noah Goldstein <goldstein.w.n@gmail.com>
Cc: GNU C Library <libc-alpha@sourceware.org>
Subject: Re: [PATCH v3 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h
Date: Wed, 4 May 2022 21:04:09 +0300 (MSK) [thread overview]
Message-ID: <dc462cf-8f1d-e7c8-8a7f-b5face4ed25@ispras.ru> (raw)
In-Reply-To: <6d61305f-58-705b-bfb8-cfa243c41d3e@ispras.ru>
Hi,
I managed to run the new benchtest; I understand how you get a 2x speedup
on long inputs now.
Tigerlake belongs to Intel CPU generations that don't perform move
elimination for general registers (along with Icelake and Sandybridge).
So register copy in preparation to shift 'h' by 5 costs an extra cycle
on the critical path.
Furthermore, h*33 + *c gets evaluated as '((h + h*32) + *c) instead of
'((h + *c) + h*32)', which prevents interleaving the additions and thus
puts one extra add on the critical path.
(gcc-11 gets this right if you assist it by writing 'h = h + *c + h*32')
So due to the above issues, on Tigerlake you get 4 cycles for the original
loop, and also 4 cycles for the modified two-at-a-time loop.
(on top of that, gcc-10 fails to eliminate extra zero-extends and ends up
with two zero-extends for *c in the loop)
Alexander
next prev parent reply other threads:[~2022-05-04 18:04 UTC|newest]
Thread overview: 167+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-14 4:12 [PATCH v1 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
2022-04-14 4:12 ` [PATCH v1 2/6] elf: Add tests for the hash functions in dl-hash.h Noah Goldstein
2022-04-14 4:12 ` [PATCH v1 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-04-14 4:12 ` [PATCH v1 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-04-14 4:12 ` [PATCH v1 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-04-14 4:12 ` [PATCH v1 6/6] elf: Optimize __dl_new_hash in dl-hash.h Noah Goldstein
2022-04-14 4:32 ` [PATCH v1 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked H.J. Lu
2022-04-14 14:56 ` Noah Goldstein
2022-04-14 14:55 ` [PATCH v2 " Noah Goldstein
2022-04-14 14:55 ` [PATCH v2 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-04-25 15:39 ` Florian Weimer
2022-04-25 15:59 ` Noah Goldstein
2022-04-14 14:55 ` [PATCH v2 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-04-25 15:38 ` Florian Weimer
2022-04-25 15:58 ` Noah Goldstein
2022-04-26 8:35 ` Florian Weimer
2022-04-26 21:39 ` Noah Goldstein
2022-04-27 10:48 ` Florian Weimer
2022-04-27 15:02 ` Noah Goldstein
2022-04-14 14:55 ` [PATCH v2 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-04-14 14:55 ` [PATCH v2 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-04-14 14:55 ` [PATCH v2 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-04-25 15:58 ` [PATCH v3 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
2022-04-25 15:58 ` [PATCH v3 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-04-25 15:58 ` [PATCH v3 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-04-25 15:58 ` [PATCH v3 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-04-25 15:58 ` [PATCH v3 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-04-25 15:58 ` [PATCH v3 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-04-25 16:01 ` [PATCH v3 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Adhemerval Zanella
2022-04-25 16:18 ` Noah Goldstein
2022-04-25 15:59 ` [PATCH v1 " Adhemerval Zanella
2022-04-25 16:16 ` Noah Goldstein
2022-04-25 16:35 ` [PATCH v3 " Noah Goldstein
2022-04-25 16:35 ` [PATCH v3 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-04-25 16:35 ` [PATCH v3 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-04-27 10:39 ` Florian Weimer
2022-04-27 16:24 ` Noah Goldstein
2022-04-25 16:35 ` [PATCH v3 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-04-25 16:36 ` [PATCH v3 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-04-27 10:47 ` Florian Weimer
2022-04-25 16:36 ` [PATCH v3 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-04-27 10:43 ` Florian Weimer
2022-04-27 16:25 ` Noah Goldstein
2022-04-27 15:02 ` Alexander Monakov
[not found] ` <CAFUsyfKeocq4VAusvnggq-NR=tOQTjrD0Z6r3CYCTjGQ=tGGSw@mail.gmail.com>
[not found] ` <f54f1ec9-fc31-283f-bce9-59fd8bda98ad@ispras.ru>
2022-04-27 16:23 ` Noah Goldstein
2022-04-28 18:03 ` Alexander Monakov
2022-05-04 18:04 ` Alexander Monakov [this message]
2022-05-05 11:07 ` Alexander Monakov
2022-05-05 15:10 ` Noah Goldstein
2022-05-05 15:26 ` Alexander Monakov
2022-05-05 18:03 ` Noah Goldstein
2022-05-05 19:37 ` Alexander Monakov
2022-05-05 22:51 ` Noah Goldstein
2022-04-27 16:19 ` [PATCH v4 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
2022-04-27 16:19 ` [PATCH v4 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-04-27 16:19 ` [PATCH v4 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-04-27 16:20 ` [PATCH v4 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-04-27 16:20 ` [PATCH v4 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-04-27 16:20 ` [PATCH v4 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-09 17:17 ` [PATCH v5 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
2022-05-09 17:17 ` [PATCH v5 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-05-09 17:17 ` [PATCH v5 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-05-09 17:17 ` [PATCH v5 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-05-09 17:17 ` [PATCH v5 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-05-09 17:17 ` [PATCH v5 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-10 11:58 ` Adhemerval Zanella
2022-05-10 15:04 ` [PATCH v6 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
2022-05-10 15:04 ` [PATCH v6 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-05-10 15:04 ` [PATCH v6 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-05-10 15:04 ` [PATCH v6 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-05-10 15:04 ` [PATCH v6 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-05-10 15:04 ` [PATCH v6 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-10 15:29 ` H.J. Lu
2022-05-10 15:31 ` H.J. Lu
2022-05-10 16:49 ` Alexander Monakov
2022-05-10 17:17 ` Noah Goldstein
2022-05-10 17:40 ` Alexander Monakov
2022-05-10 23:30 ` [PATCH v7 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
2022-05-10 23:30 ` [PATCH v7 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-05-10 23:30 ` [PATCH v7 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-05-10 23:30 ` [PATCH v7 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-05-10 23:30 ` [PATCH v7 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-05-10 23:30 ` [PATCH v7 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-10 23:46 ` H.J. Lu
2022-05-11 3:07 ` Noah Goldstein
2022-05-11 3:06 ` [PATCH v8 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
2022-05-11 3:06 ` [PATCH v8 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-05-11 3:06 ` [PATCH v8 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-05-11 3:06 ` [PATCH v8 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-05-11 3:06 ` [PATCH v8 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-05-11 3:06 ` [PATCH v8 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-16 14:12 ` Siddhesh Poyarekar
2022-05-16 14:31 ` Alexander Monakov
2022-05-16 16:23 ` Siddhesh Poyarekar
2022-05-16 16:38 ` Noah Goldstein
2022-05-16 16:44 ` Siddhesh Poyarekar
2022-05-16 20:32 ` Noah Goldstein
2022-05-16 18:09 ` Alexander Monakov
2022-05-16 18:47 ` Siddhesh Poyarekar
2022-05-16 19:28 ` Alexander Monakov
2022-05-16 19:35 ` Noah Goldstein
2022-05-16 19:41 ` Alexander Monakov
2022-05-16 19:47 ` Adhemerval Zanella
2022-05-16 20:00 ` Alexander Monakov
2022-05-16 20:08 ` Adhemerval Zanella
2022-05-16 20:27 ` Alexander Monakov
2022-05-16 19:48 ` Noah Goldstein
2022-05-16 20:33 ` Alexander Monakov
2022-05-16 21:40 ` Noah Goldstein
2022-05-17 1:45 ` Siddhesh Poyarekar
2022-05-16 13:56 ` [PATCH v8 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Siddhesh Poyarekar
2022-05-16 20:31 ` Noah Goldstein
2022-05-16 20:29 ` [PATCH v9 " Noah Goldstein
2022-05-16 20:30 ` [PATCH v9 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-05-17 4:19 ` Siddhesh Poyarekar
2022-05-18 17:29 ` Noah Goldstein
2022-05-16 20:30 ` [PATCH v9 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-05-17 4:32 ` Siddhesh Poyarekar
2022-05-18 17:30 ` Noah Goldstein
2022-05-16 20:30 ` [PATCH v9 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-05-17 4:52 ` Siddhesh Poyarekar
2022-05-18 17:33 ` Noah Goldstein
2022-05-16 20:30 ` [PATCH v9 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-05-17 5:11 ` Siddhesh Poyarekar
2022-05-18 17:34 ` Noah Goldstein
2022-05-18 17:35 ` Noah Goldstein
2022-05-16 20:30 ` [PATCH v9 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-17 5:12 ` Siddhesh Poyarekar
2022-05-18 17:38 ` Noah Goldstein
2022-05-19 15:59 ` Siddhesh Poyarekar
2022-05-19 16:54 ` DJ Delorie
2022-05-17 3:34 ` [PATCH v9 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Siddhesh Poyarekar
2022-05-18 17:28 ` Noah Goldstein
2022-05-18 17:26 ` [PATCH v10 " Noah Goldstein
2022-05-18 17:26 ` [PATCH v10 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-05-19 14:49 ` Siddhesh Poyarekar
2022-05-18 17:26 ` [PATCH v10 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-05-19 15:09 ` Siddhesh Poyarekar
2022-05-19 15:40 ` Siddhesh Poyarekar
2022-05-19 22:20 ` Noah Goldstein
2022-05-18 17:26 ` [PATCH v10 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-05-19 15:34 ` Siddhesh Poyarekar
2022-05-19 22:20 ` Noah Goldstein
2022-05-18 17:26 ` [PATCH v10 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-05-19 15:41 ` Siddhesh Poyarekar
2022-05-19 22:21 ` Noah Goldstein
2022-05-18 17:26 ` [PATCH v10 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-18 17:32 ` H.J. Lu
2022-05-18 17:39 ` Noah Goldstein
2022-05-19 7:53 ` Siddhesh Poyarekar
2022-05-19 15:55 ` Siddhesh Poyarekar
2022-05-19 22:22 ` Noah Goldstein
2022-05-19 14:47 ` [PATCH v10 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Siddhesh Poyarekar
2022-05-19 14:50 ` Noah Goldstein
2022-05-19 14:56 ` Siddhesh Poyarekar
2022-05-19 22:17 ` [PATCH v11 " Noah Goldstein
2022-05-19 22:17 ` [PATCH v11 2/6] elf: Add tests for the dl hash funcs (_dl_new_hash and _dl_elf_hash) Noah Goldstein
2022-05-19 22:19 ` Noah Goldstein
2022-05-19 22:18 ` [PATCH v11 3/6] nss: Add tests for the nss_hash in nss_hash.h Noah Goldstein
2022-05-23 7:42 ` Siddhesh Poyarekar
2022-05-19 22:18 ` [PATCH v11 4/6] benchtests: Add benchtests for dl_elf_hash, dl_new_hash and nss_hash Noah Goldstein
2022-05-23 7:44 ` Siddhesh Poyarekar
2022-05-19 22:18 ` [PATCH v11 5/6] nss: Optimize nss_hash in nss_hash.c Noah Goldstein
2022-05-23 7:44 ` Siddhesh Poyarekar
2022-05-19 22:18 ` [PATCH v11 6/6] elf: Optimize _dl_new_hash in dl-new-hash.h Noah Goldstein
2022-05-23 7:46 ` Siddhesh Poyarekar
2022-05-19 22:18 ` [PATCH v11 1/6] elf: Refactor dl_new_hash so it can be tested / benchmarked Noah Goldstein
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