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Date: Wed, 17 Jun 2009 21:20:08 -0500 From: Jason Wessel <jason.wessel@...driver.com> To: greg@...ah.com, alan@...rguk.ukuu.org.uk Cc: linux-kernel@...r.kernel.org, Jason Wessel <jason.wessel@...driver.com> Subject: [PATCH 2/3] usb-serial: regression fix to move sysrq from hot path A performance regression was introduced by commit: 98fcb5f78165b8a3d93870ad7afd4d9ebbb8b43a The sysrq handling should only get executed if the attached usb serial device is acting as a serial system console. A serial system console has a very low input throughput vs a 3g usb modem which pushes bytes through the same interface at a high rate. Entire strings of output can be processed via the tty input when the device is not a console. Signed-off-by: Jason Wessel <jason.wessel@...driver.com> --- drivers/usb/serial/generic.c | 16 ++++++++++++---- 1 files changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c index 932d624..82b8883 100644 --- a/drivers/usb/serial/generic.c +++ b/drivers/usb/serial/generic.c @@ -425,11 +425,19 @@ static void flush_and_resubmit_read_urb(struct usb_serial_port *port) goto done; /* Push data to tty */ - for (i = 0; i < urb->actual_length; i++, ch++) { - if (!usb_serial_handle_sysrq_char(port, *ch)) - tty_insert_flip_char(tty, *ch, TTY_NORMAL); + if (port->console) { + for (i = 0; i < urb->actual_length; i++, ch++) { + if (!usb_serial_handle_sysrq_char(port, *ch)) + tty_insert_flip_char(tty, *ch, TTY_NORMAL); + } + tty_flip_buffer_push(tty); + } else if (urb->actual_length) { + i = tty_buffer_request_room(tty, urb->actual_length); + if (i) { + tty_insert_flip_string(tty, urb->transfer_buffer, i); + tty_flip_buffer_push(tty); + } } - tty_flip_buffer_push(tty); tty_kref_put(tty); done: usb_serial_generic_resubmit_read_urb(port, GFP_ATOMIC); -- 1.6.3.1.9.g95405b -- 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/
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