![]() Using delayed-work for tty flip buffers ends up causing us to wait for the next tick to complete some actions. That's usually not all that noticeable, but for certain latency-critical workloads it ends up being totally unacceptable. As an extreme case of this, passing a token back-and-forth over a pty will take two ticks per iteration, so even just a thousand iterations will take 8 seconds assuming a common 250Hz configuration. Avoiding the whole delayed work issue brings that ping-pong test-case down to 0.009s on my machine. In more practical terms, this latency has been a performance problem for things like dive computer simulators (simulating the serial interface using the ptys) and for other environments (Alan mentions a CP/M emulator). Reported-by: Jef Driesen <jefdriesen@telenet.be> Acked-by: Greg KH <gregkh@suse.de> Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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hvc | ||
ipwireless | ||
serial | ||
vt | ||
amiserial.c | ||
bfin_jtag_comm.c | ||
cyclades.c | ||
isicom.c | ||
Kconfig | ||
Makefile | ||
moxa.c | ||
moxa.h | ||
mxser.c | ||
mxser.h | ||
n_gsm.c | ||
n_hdlc.c | ||
n_r3964.c | ||
n_tty.c | ||
nozomi.c | ||
pty.c | ||
rocket.c | ||
rocket.h | ||
rocket_int.h | ||
synclink.c | ||
synclink_gt.c | ||
synclinkmp.c | ||
sysrq.c | ||
tty_audit.c | ||
tty_buffer.c | ||
tty_io.c | ||
tty_ioctl.c | ||
tty_ldisc.c | ||
tty_mutex.c | ||
tty_port.c |