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From: Pavel Begunkov <asml.silence@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Pavel Machek <pavel@denx.de>,
	Greg KH <gregkh@linuxfoundation.org>,
	Jan Ziak <0xe2.0x9a.0x9b@gmail.com>,
	Linux API <linux-api@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	linux-man <linux-man@vger.kernel.org>,
	Michael Kerrisk <mtk.manpages@gmail.com>,
	shuah@kernel.org, Al Viro <viro@zeniv.linux.org.uk>,
	io-uring@vger.kernel.org
Subject: Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster
Date: Wed, 15 Jul 2020 12:00:19 +0300	[thread overview]
Message-ID: <df17d629-59ea-3262-fae4-28c05e5c9294@gmail.com> (raw)
In-Reply-To: <b3adac43-f4ec-7820-1297-59eee206f308@gmail.com>

On 15/07/2020 11:49, Pavel Begunkov wrote:
> On 15/07/2020 11:41, Miklos Szeredi wrote:
>> On Wed, Jul 15, 2020 at 10:33 AM Pavel Begunkov <asml.silence@gmail.com> wrote:
>>>
>>> On 14/07/2020 14:55, Miklos Szeredi wrote:
>>>> On Tue, Jul 14, 2020 at 1:36 PM Pavel Begunkov <asml.silence@gmail.com> wrote:
>>>>>
>>>>> On 14/07/2020 11:07, Miklos Szeredi wrote:
>>>>>> On Tue, Jul 14, 2020 at 8:51 AM Pavel Machek <pavel@denx.de> wrote:
>>>>>>>
>>>>>>> Hi!
>>>>>>>
>>>>>>>>> At first, I thought that the proposed system call is capable of
>>>>>>>>> reading *multiple* small files using a single system call - which
>>>>>>>>> would help increase HDD/SSD queue utilization and increase IOPS (I/O
>>>>>>>>> operations per second) - but that isn't the case and the proposed
>>>>>>>>> system call can read just a single file.
>>>>>>>>
>>>>>>>> If you want to do this for multple files, use io_ring, that's what it
>>>>>>>> was designed for.  I think Jens was going to be adding support for the
>>>>>>>> open/read/close pattern to it as well, after some other more pressing
>>>>>>>> features/fixes were finished.
>>>>>>>
>>>>>>> What about... just using io_uring for single file, too? I'm pretty
>>>>>>> sure it can be wrapped in a library that is simple to use, avoiding
>>>>>>> need for new syscall.
>>>>>>
>>>>>> Just wondering:  is there a plan to add strace support to io_uring?
>>>>>> And I don't just mean the syscalls associated with io_uring, but
>>>>>> tracing the ring itself.
>>>>>
>>>>> What kind of support do you mean? io_uring is asynchronous in nature
>>>>> with all intrinsic tracing/debugging/etc. problems of such APIs.
>>>>> And there are a lot of handy trace points, are those not enough?
>>>>>
>>>>> Though, this can be an interesting project to rethink how async
>>>>> APIs are worked with.
>>>>
>>>> Yeah, it's an interesting problem.  The uring has the same events, as
>>>> far as I understand, that are recorded in a multithreaded strace
>>>> output (syscall entry, syscall exit); nothing more is needed>
>>>> I do think this needs to be integrated into strace(1), otherwise the
>>>> usefulness of that tool (which I think is *very* high) would go down
>>>> drastically as io_uring usage goes up.
>>>
>>> Not touching the topic of usefulness of strace + io_uring, but I'd rather
>>> have a tool that solves a problem, than a problem that created and honed
>>> for a tool.
>>
>> Sorry, I'm not getting the metaphor.  Can you please elaborate?
> 
> Sure, I mean _if_ there are tools that conceptually suit better, I'd
> prefer to work with them, then trying to shove a new and possibly alien
> infrastructure into strace.
> 
> But my knowledge of strace is very limited, so can't tell whether that's
> the case. E.g. can it utilise static trace points?

I think, if you're going to push this idea, we should start a new thread
CC'ing strace devs.
	
-- 
Pavel Begunkov

  reply	other threads:[~2020-07-15  9:02 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-05  2:06 Jan Ziak
2020-07-05  2:16 ` Matthew Wilcox
2020-07-05  2:46   ` Jan Ziak
2020-07-05  3:12     ` Matthew Wilcox
2020-07-05  3:18       ` Jan Ziak
2020-07-05  3:27         ` Matthew Wilcox
2020-07-05  4:09           ` Jan Ziak
2020-07-05 11:58             ` Greg KH
2020-07-06  6:07               ` Jan Ziak
2020-07-06 11:11                 ` Matthew Wilcox
2020-07-06 11:18                 ` Greg KH
2020-07-05  8:07           ` Vito Caputo
2020-07-05 11:44             ` Greg KH
2020-07-05 20:34               ` Vito Caputo
2020-07-05  6:32     ` Andreas Dilger
2020-07-05  7:25       ` Jan Ziak
2020-07-05 12:00         ` Greg KH
2020-07-05 11:50 ` Greg KH
2020-07-14  6:51   ` Pavel Machek
2020-07-14  8:07     ` Miklos Szeredi
2020-07-14 11:34       ` Pavel Begunkov
2020-07-14 11:55         ` Miklos Szeredi
2020-07-15  8:31           ` Pavel Begunkov
2020-07-15  8:41             ` Miklos Szeredi
2020-07-15  8:49               ` Pavel Begunkov
2020-07-15  9:00                 ` Pavel Begunkov [this message]
2020-07-15 11:17                   ` Miklos Szeredi
  -- strict thread matches above, loose matches on Subject: below --
2020-07-04 14:02 Greg Kroah-Hartman
2020-07-04 19:30 ` Al Viro
2020-07-05 11:47   ` Greg Kroah-Hartman
2020-07-06 17:25 ` Dave Martin

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