From: Steven Rostedt <rostedt@goodmis.org>
To: Slavomir Kaslev <kaslevs@vmware.com>
Cc: "linux-trace-devel@vger.kernel.org" <linux-trace-devel@vger.kernel.org>
Subject: Re: [RFC PATCH v9 11/11] trace-cmd: Add splice() recording from FIFO without additional pipe buffer
Date: Wed, 3 Apr 2019 09:25:17 -0400 [thread overview]
Message-ID: <20190403092517.1c999a83@gandalf.local.home> (raw)
In-Reply-To: <fe5cbfd1d91e83636d6b32c2522411aed471958d.camel@vmware.com>
On Wed, 3 Apr 2019 13:11:07 +0000
Slavomir Kaslev <kaslevs@vmware.com> wrote:
> >
> > Why the polling code, and not just block on splice?
>
> To work around older kernels that don't have the splice(2)
> O_NONBLOCKING fix[1] for pipes.
>
> An alternative would be to configure SIGINT not to auto restart
> syscalls (which is the default afaik). Then splice(2) will return
> EAGAIN and will can restart it with SPLICE_F_NONBLOCK flag on.
There needs to be a comment explaining its existence then, and perhaps
we can do a check at the beginning (someplace else) to see if the fix is
in, and then skip this part if it is.
-- Steve
prev parent reply other threads:[~2019-04-03 13:25 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-02 13:45 [RFC PATCH v9 00/11] Add VM kernel tracing over vsockets and FIFOs Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 01/11] trace-cmd: Make ports unsigned int Slavomir Kaslev
2019-04-03 13:00 ` Steven Rostedt
2019-04-03 13:14 ` Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 02/11] trace-cmd: Detect if vsockets are available Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 03/11] trace-cmd: Add tracecmd_create_recorder_virt function Slavomir Kaslev
2019-04-03 13:02 ` Steven Rostedt
2019-04-03 13:12 ` Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 04/11] trace-cmd: Add TRACE_REQ and TRACE_RESP messages Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 05/11] trace-cmd: Add buffer instance flags for tracing in guest and agent context Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 06/11] trace-cmd: Add VM kernel tracing over vsockets transport Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 07/11] trace-cmd: Use splice(2) for vsockets if available Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 08/11] trace-cmd: Add `trace-cmd setup-guest` command Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 09/11] trace-cmd: Try to autodetect number of guest CPUs in setup-guest if not specified Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 10/11] trace-cmd: Add setup-guest flag for attaching FIFOs to the guest VM config Slavomir Kaslev
2019-04-02 13:45 ` [RFC PATCH v9 11/11] trace-cmd: Add splice() recording from FIFO without additional pipe buffer Slavomir Kaslev
2019-04-03 12:55 ` Steven Rostedt
2019-04-03 13:11 ` Slavomir Kaslev
2019-04-03 13:16 ` Slavomir Kaslev
2019-04-03 13:25 ` Steven Rostedt [this message]
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