linux-kernel - Re: [PATCH] perf record: mmap output file

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 15 Oct 2013 17:17:42 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	David Ahern <dsahern@...il.com>, acme@...stprotocols.net,
	linux-kernel@...r.kernel.org,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Jiri Olsa <jolsa@...hat.com>, Mike Galbraith <efault@....de>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH] perf record: mmap output file - v2

On Tue, 15 Oct 2013 09:25:40 +0200, Ingo Molnar wrote:
> * Namhyung Kim <namhyung@...nel.org> wrote:
>> No, st_size is bigger than rec->bytes_written due to the 
>> perf_file_header which is written without updating rec->bytes_written.
>
> Since all this is code that executes once during __cmd_record(), is this 
> all about the header writeout?
>
> That is what confused me about the stat() call and that's messy really: we 
> are the ones who write the file header, we have a very good idea about how 
> many bytes we wrote to the file! It should be entirely unnecessary to lose 
> that information and then execute a system call to recover that 
> information...

Right, I think session->header.data_offset has the info already.

Thanks,
Namhyung
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/