From: Stas Sergeev <stsp@list.ru>
To: Johan Hovold <jhovold@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
Jarkko Huijts <jarkko.huijts@gmail.com>,
Alan Cox <alan@linux.intel.com>,
linux-usb@vger.kernel.org, linux-serial@vger.kernel.org,
Linux kernel <linux-kernel@vger.kernel.org>,
Caylan Van Larson <i@caylan.net>,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: Regression: ftdi_sio is slow (since Wed Oct 10 15:05:06 2012)
Date: Sat, 04 May 2013 16:44:05 +0400 [thread overview]
Message-ID: <51850295.6020601@list.ru> (raw)
In-Reply-To: <20130504111535.GC16818@localhost>
04.05.2013 15:15, Johan Hovold пишет:
> The query takes longer than the transmit at decent baudrates (>=38k)
> and under the assumption that flow control isn't causing any delays.
>
> But you do have a point, and I have been meaning to look into whether
> the added overhead of checking the hardware buffers could be mitigated
> by adding wait_until_sent support to usb-serial. This way the we would
> only query the hardware buffers on tty_wait_until_sent (e.g. at close)
> and select and TIOCMOUTQ would not suffer. This is also the way things
> are handled in serial_core.
Thanks for taking a look.
Indeed, it seems .wait_until_sent is the best candidate for that
kind of things, and the patch in question would even match its
description be it using .wait_until_sent and not .chars_in_buffer.
Please count on testing your patches here when they are ready.
next prev parent reply other threads:[~2013-05-04 11:46 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-03 15:02 Regression: ftdi_sio is slow (since Wed Oct 10 15:05:06 2012) Stas Sergeev
2013-05-03 16:30 ` Greg KH
2013-05-03 17:38 ` Stas Sergeev
2013-05-03 16:52 ` Greg KH
2013-05-03 18:05 ` Stas Sergeev
2013-05-03 17:16 ` Greg KH
2013-05-03 18:27 ` Stas Sergeev
2013-05-03 20:34 ` Greg KH
2013-05-03 21:50 ` Stas Sergeev
2013-05-04 11:15 ` Johan Hovold
2013-05-04 11:39 ` Peter Hurley
2013-05-05 18:29 ` Johan Hovold
2013-05-05 18:32 ` [PATCH 0/7] USB: serial: add wait_until_sent-support Johan Hovold
2013-05-05 18:32 ` [PATCH 1/7] USB: serial: add wait_until_sent operation Johan Hovold
2013-05-05 18:32 ` [PATCH 2/7] USB: serial: add generic wait_until_sent implementation Johan Hovold
2013-05-08 14:25 ` Stas Sergeev
2013-05-08 15:48 ` Johan Hovold
2013-05-08 15:51 ` [PATCH v2 2/8] " Johan Hovold
2013-05-05 18:32 ` [PATCH 3/7] USB: ftdi_sio: clean up get_modem_status Johan Hovold
2013-05-05 18:32 ` [PATCH 4/7] USB: ftdi_sio: fix chars_in_buffer overhead Johan Hovold
2013-05-05 18:32 ` [PATCH 5/7] USB: io_ti: " Johan Hovold
2013-05-05 18:32 ` [PATCH 6/7] USB: ti_usb_3410_5052: " Johan Hovold
2013-05-05 18:32 ` [PATCH 7/7] USB: serial: clean up chars_in_buffer Johan Hovold
[not found] ` <81D166EE-BB85-4A72-A6FA-A1F6B5633CB0@caylan.net>
2013-05-20 10:07 ` [PATCH 0/7] USB: serial: add wait_until_sent-support Johan Hovold
2013-05-04 12:44 ` Stas Sergeev [this message]
2013-05-04 9:37 ` Regression: ftdi_sio is slow (since Wed Oct 10 15:05:06 2012) Stas Sergeev
2013-05-03 18:15 ` Stas Sergeev
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