From patchwork Thu Jan 4 13:29:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe JAILLET X-Patchwork-Id: 13511118 Received: from smtp.smtpout.orange.fr (smtp-15.smtpout.orange.fr [80.12.242.15]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0B39E22313 for ; Thu, 4 Jan 2024 13:37:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=wanadoo.fr Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=wanadoo.fr Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=wanadoo.fr header.i=@wanadoo.fr header.b="Iod9vDX/" Received: from pop-os.home ([92.140.202.140]) by smtp.orange.fr with ESMTPA id LNn9rqZHtmbVqLNn9rhL4z; Thu, 04 Jan 2024 14:29:48 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wanadoo.fr; s=t20230301; t=1704374988; bh=ciTbDjeP+vCKPdJby2wMqEkjO/zLT5PPfRKymuvu7Ls=; h=From:To:Cc:Subject:Date; b=Iod9vDX/tgK1aAj3D0pbcF1SNX2aOulCB5ziVBgXc2wj6sOGEGBmLWICLdqZHZt1x UlTjdr32do3p5szUwUxlGYJXZCS9asBZSRogiJqv6CaSbTb6kt9vprVOAq9m0B1Okf //EXruuhFxkXyxmZeYu0nHTfn0zzJkFcd3ymeIDLQzLloLnZkyaN43xELjdoI9Ys+y DIW2rbvPF+wBN8W2CB8VEm4/9Mf/bxfNzmMGqUW1d1P8S8t0mu127k442K2KggsUsv GC1Jh3+mYzZMGZXRoxl6tidDt02gehE5jJOb8Fz3axGOJPBtvHnAsMeSXwnXWhaulV N60RtHWbmS6zA== X-ME-Helo: pop-os.home X-ME-Auth: Y2hyaXN0b3BoZS5qYWlsbGV0QHdhbmFkb28uZnI= X-ME-Date: Thu, 04 Jan 2024 14:29:48 +0100 X-ME-IP: 92.140.202.140 From: Christophe JAILLET To: Alexander Viro , Christian Brauner , Jan Kara Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Christophe JAILLET , linux-fsdevel@vger.kernel.org Subject: [PATCH] seq_file: Optimize seq_puts() Date: Thu, 4 Jan 2024 14:29:37 +0100 Message-Id: <5c4f7ad7b88f5026940efa9c8be36a58755ec1b3.1704374916.git.christophe.jaillet@wanadoo.fr> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Most of seq_puts() usages are done with a string literal. In such cases, the length of the string car be computed at compile time in order to save a strlen() call at run-time. seq_write() can then be used instead. This saves a few cycles. To have an estimation of how often this optimization triggers: $ git grep seq_puts.*\" | wc -l 3391 Signed-off-by: Christophe JAILLET --- Checked by comparing the output of a few .s files. Here is one of these outputs: $ diff -u drivers/clk/clk.s.old drivers/clk/clk.s | grep -C6 seq_w call clk_prepare_unlock # # drivers/clk/clk.c:3320: seq_puts(s, "}\n"); movq %r12, %rdi # s, + movl $2, %edx #, movq $.LC66, %rsi #, - call seq_puts # + call seq_write # call __tsan_func_exit # # drivers/clk/clk.c:3322: } xorl %eax, %eax # @@ -34520,6 +34521,7 @@ popq %rbp # popq %r12 # -- # drivers/clk/clk.c:3205: seq_puts(s, "-----"); call __sanitizer_cov_trace_pc # + movl $5, %edx #, movq $.LC72, %rsi #, movq %r13, %rdi # s, - call seq_puts # + call seq_write # jmp .L2134 # .L2144: # drivers/clk/clk.c:1793: return clk_core_get_accuracy_no_lock(core); @@ -35225,20 +35228,23 @@ leaq 240(%r12), %rdi #, tmp95 call __tsan_read8 # -- movq %r12, %rdi # s, + movq $.LC77, %rsi #, # drivers/clk/clk.c:3244: struct hlist_head **lists = s->private; movq 240(%r12), %rbp # s_9(D)->private, lists # drivers/clk/clk.c:3246: seq_puts(s, " enable prepare protect duty hardware connection\n"); - call seq_puts # + call seq_write # # drivers/clk/clk.c:3247: seq_puts(s, " clock count count count rate accuracy phase cycle enable consumer id\n"); + movl $142, %edx #, movq $.LC78, %rsi #, movq %r12, %rdi # s, - call seq_puts # + call seq_write # # drivers/clk/clk.c:3248: seq_puts(s, "---------------------------------------------------------------------------------------------------------------------------------------------\n"); + movl $142, %edx #, movq $.LC79, %rsi #, movq %r12, %rdi # s, - call seq_puts # + call seq_write # # drivers/clk/clk.c:3251: clk_prepare_lock(); call clk_prepare_lock # .L2207: @@ -37511,7 +37517,7 @@ subq $16, %rsp #, # drivers/clk/clk.c:3082: { --- fs/seq_file.c | 4 ++-- include/linux/seq_file.h | 10 +++++++++- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/fs/seq_file.c b/fs/seq_file.c index f5fdaf3b1572..8ef0a07033ca 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -669,7 +669,7 @@ void seq_putc(struct seq_file *m, char c) } EXPORT_SYMBOL(seq_putc); -void seq_puts(struct seq_file *m, const char *s) +void __seq_puts(struct seq_file *m, const char *s) { int len = strlen(s); @@ -680,7 +680,7 @@ void seq_puts(struct seq_file *m, const char *s) memcpy(m->buf + m->count, s, len); m->count += len; } -EXPORT_SYMBOL(seq_puts); +EXPORT_SYMBOL(__seq_puts); /** * seq_put_decimal_ull_width - A helper routine for putting decimal numbers diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index 234bcdb1fba4..15abf45d62c5 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -118,7 +118,15 @@ void seq_vprintf(struct seq_file *m, const char *fmt, va_list args); __printf(2, 3) void seq_printf(struct seq_file *m, const char *fmt, ...); void seq_putc(struct seq_file *m, char c); -void seq_puts(struct seq_file *m, const char *s); +void __seq_puts(struct seq_file *m, const char *s); +#define seq_puts(m, s) \ +do { \ + if (__builtin_constant_p(s)) \ + seq_write(m, s, __builtin_strlen(s)); \ + else \ + __seq_puts(m, s); \ +} while (0) + void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter, unsigned long long num, unsigned int width); void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,