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From: Petr Mladek <pmladek@suse.com>
To: Zhen Lei <thunder.leizhen@huawei.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>, Jiri Olsa <jolsa@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Luis Chamberlain <mcgrof@kernel.org>,
	linux-modules@vger.kernel.org
Subject: Re: [PATCH v4 2/8] scripts/kallsyms: ensure that all possible combinations are compressed
Date: Wed, 21 Sep 2022 10:00:07 +0200	[thread overview]
Message-ID: <YyrEh+fbhYh6ltLp@alley> (raw)
In-Reply-To: <20220920071317.1787-3-thunder.leizhen@huawei.com>

On Tue 2022-09-20 15:13:11, Zhen Lei wrote:
> For a symbol, there may be more than one place that can be merged. For
> example: nfs_fs_proc_net_init, there are two "f"+"s_" combinations.
> And we're only compressing the first combination at the moment.

Really?

> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index 8caccc8f4a23703..3319d9f38d7a5f2 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -553,7 +553,7 @@ static void compress_symbols(const unsigned char *str, int idx)
>  	unsigned char *p1, *p2;
>  
>  	for (i = 0; i < table_cnt; i++) {
> -
> +retry:
>  		len = table[i]->len;
>  		p1 = table[i]->sym;
>  
> @@ -585,6 +585,9 @@ static void compress_symbols(const unsigned char *str, int idx)
>  
>  		/* increase the counts for this symbol's new tokens */
>  		learn_symbol(table[i]->sym, len);
> +
> +		/* May be more than one place that can be merged, try again */
> +		goto retry;
>  	}
>  }

My understanding is that the code already tries to find the same
token several times. Here are the important parts of the existing
code:

static void compress_symbols(const unsigned char *str, int idx)
{

		p2 = find_token(p1, len, str);

		do {
			/* replace the found token with idx */
			*p2 = idx;
			[...]

			/* find the token on the symbol */
			p2 = find_token(p1, size, str);

		} while (p2);

Best Regards,
Petr

  reply	other threads:[~2022-09-21  8:00 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-20  7:13 [PATCH v4 0/8] kallsyms: Optimizes the performance of lookup symbols Zhen Lei
2022-09-20  7:13 ` [PATCH v4 1/8] scripts/kallsyms: rename build_initial_tok_table() Zhen Lei
2022-09-21  7:47   ` Petr Mladek
2022-09-20  7:13 ` [PATCH v4 2/8] scripts/kallsyms: ensure that all possible combinations are compressed Zhen Lei
2022-09-21  8:00   ` Petr Mladek [this message]
2022-09-21  8:31     ` Leizhen (ThunderTown)
2022-09-21 12:46       ` Leizhen (ThunderTown)
2022-09-20  7:13 ` [PATCH v4 3/8] scripts/kallsyms: don't compress symbol types Zhen Lei
2022-09-21  9:00   ` Petr Mladek
2022-09-21 13:13     ` Leizhen (ThunderTown)
2022-09-20  7:13 ` [PATCH v4 4/8] kallsyms: Improve the performance of kallsyms_lookup_name() Zhen Lei
2022-09-21 15:25   ` Petr Mladek
2022-09-22  2:15     ` Leizhen (ThunderTown)
2022-09-22  7:02       ` Petr Mladek
2022-09-22  7:21         ` Leizhen (ThunderTown)
2022-09-22 13:17           ` Petr Mladek
2022-09-28  1:35         ` Leizhen (ThunderTown)
2022-09-30 11:37           ` Leizhen (ThunderTown)
2022-09-22  7:14       ` Leizhen (ThunderTown)
2022-09-20  7:13 ` [PATCH v4 5/8] kallsyms: Add helper kallsyms_on_each_match_symbol() Zhen Lei
2022-09-21 15:30   ` Petr Mladek
2022-09-22  2:16     ` Leizhen (ThunderTown)
2022-09-20  7:13 ` [PATCH v4 6/8] livepatch: Use kallsyms_on_each_match_symbol() to improve performance Zhen Lei
2022-09-20  7:13 ` [PATCH v4 7/8] livepatch: Improve the search performance of module_kallsyms_on_each_symbol() Zhen Lei
2022-09-20  7:13 ` [PATCH v4 8/8] kallsyms: Add self-test facility Zhen Lei

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