linux-kernel - Re: [PATCH v9 2/3]: perf record: enable asynchronous trace writing

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <558ec0ad-7083-e4ed-e6bb-9b90c86b20bf@linux.intel.com>
Date:   Fri, 5 Oct 2018 18:53:17 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>, kernel-team@....com
Subject: Re: [PATCH v9 2/3]: perf record: enable asynchronous trace writing

Hi,
On 05.10.2018 14:50, Alexey Budankov wrote:<SNIP>
> 
> According to docs [1] ftruncate() does not advance file pos 
> which is essential here.
> 

Ideally, the both lseek() syscalls in every loop iteration can be
replaced by the only two syscalls just before and after the loop and
advancing *in-flight* off file pos value at perf_mmap__aio_push() 
after every successful record__aio_pushfn().

Thanks,
Alexey