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Commit e60d27c4 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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n_tty: Factor LNEXT processing from per-char i/o path 

LNEXT processing accounts for ~15% of total cpu time in end-to-end
tty i/o; factor the lnext test/clear from the per-char i/o path.

Instead, attempt to immediately handle the literal next char if not
at the end of this received buffer; otherwise, handle the first char
of the next received buffer as the literal next char, then continue
with normal i/o.
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 4b293492
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Showing with 94 additions and 72 deletions
drivers/tty/n_tty.c
View file @ e60d27c4
......@@ -1249,9 +1249,11 @@ n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c)
* caller holds non-exclusive termios_rwsem
* publishes canon_head if canonical mode is active
* otherwise, publishes read_head via put_tty_queue()
*
* Returns 1 if LNEXT was received, else returns 0
*/
static void
static int
n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
{
struct n_tty_data *ldata = tty->disc_data;
......@@ -1261,24 +1263,24 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
if (c == START_CHAR(tty)) {
start_tty(tty);
commit_echoes(tty);
return;
return 0;
}
if (c == STOP_CHAR(tty)) {
stop_tty(tty);
return;
return 0;
}
}
if (L_ISIG(tty)) {
if (c == INTR_CHAR(tty)) {
n_tty_receive_signal_char(tty, SIGINT, c);
return;
return 0;
} else if (c == QUIT_CHAR(tty)) {
n_tty_receive_signal_char(tty, SIGQUIT, c);
return;
return 0;
} else if (c == SUSP_CHAR(tty)) {
n_tty_receive_signal_char(tty, SIGTSTP, c);
return;
return 0;
}
}
......@@ -1289,7 +1291,7 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
if (c == '\r') {
if (I_IGNCR(tty))
return;
return 0;
if (I_ICRNL(tty))
c = '\n';
} else if (c == '\n' && I_INLCR(tty))
......@@ -1300,7 +1302,7 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
(c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
eraser(c, tty);
commit_echoes(tty);
return;
return 0;
}
if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
ldata->lnext = 1;
......@@ -1312,10 +1314,9 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
commit_echoes(tty);
}
}
return;
return 1;
}
if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
L_IEXTEN(tty)) {
if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) {
size_t tail = ldata->canon_head;
finish_erasing(ldata);
......@@ -1326,7 +1327,7 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
tail++;
}
commit_echoes(tty);
return;
return 0;
}
if (c == '\n') {
if (L_ECHO(tty) || L_ECHONL(tty)) {
......@@ -1367,7 +1368,7 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
kill_fasync(&tty->fasync, SIGIO, POLL_IN);
if (waitqueue_active(&tty->read_wait))
wake_up_interruptible(&tty->read_wait);
return;
return 0;
}
}
......@@ -1389,24 +1390,16 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c)
put_tty_queue(c, ldata);
put_tty_queue(c, ldata);
return 0;
}
static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
static inline void
n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c)
{
struct n_tty_data *ldata = tty->disc_data;
int parmrk;
/*
* If the previous character was LNEXT, or we know that this
* character is not one of the characters that we'll have to
* handle specially, do shortcut processing to speed things
* up.
*/
if (!test_bit(c, ldata->char_map) || ldata->lnext) {
ldata->lnext = 0;
if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
I_IXANY(tty)) {
if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
start_tty(tty);
process_echoes(tty);
}
......@@ -1422,10 +1415,11 @@ static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
if (parmrk)
put_tty_queue(c, ldata);
put_tty_queue(c, ldata);
return;
}
}
n_tty_receive_char_special(tty, c);
static inline void n_tty_receive_char(struct tty_struct *tty, unsigned char c)
{
n_tty_receive_char_inline(tty, c);
}
static inline void
......@@ -1433,17 +1427,7 @@ n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
{
struct n_tty_data *ldata = tty->disc_data;
/*
* If the previous character was LNEXT, or we know that this
* character is not one of the characters that we'll have to
* handle specially, do shortcut processing to speed things
* up.
*/
if (!test_bit(c, ldata->char_map) || ldata->lnext) {
ldata->lnext = 0;
if (tty->stopped && !tty->flow_stopped && I_IXON(tty) &&
I_IXANY(tty)) {
if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) {
start_tty(tty);
process_echoes(tty);
}
......@@ -1456,10 +1440,6 @@ n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c)
commit_echoes(tty);
}
put_tty_queue(c, ldata);
return;
}
n_tty_receive_char_special(tty, c);
}
static inline void
......@@ -1506,6 +1486,22 @@ n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag)
}
}
static void
n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag)
{
struct n_tty_data *ldata = tty->disc_data;
ldata->lnext = 0;
if (likely(flag == TTY_NORMAL)) {
if (I_ISTRIP(tty))
c &= 0x7f;
if (I_IUCLC(tty) && L_IEXTEN(tty))
c = tolower(c);
n_tty_receive_char(tty, c);
} else
n_tty_receive_char_flagged(tty, c, flag);
}
/**
* n_tty_receive_buf - data receive
* @tty: terminal device
......@@ -1599,7 +1595,14 @@ n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp,
put_tty_queue(c, ldata);
continue;
}
n_tty_receive_char(tty, c);
if (!test_bit(c, ldata->char_map))
n_tty_receive_char_inline(tty, c);
else if (n_tty_receive_char_special(tty, c) && count) {
if (fp)
flag = *fp++;
n_tty_receive_char_lnext(tty, *cp++, flag);
count--;
}
} else
n_tty_receive_char_flagged(tty, *cp++, flag);
}
......@@ -1609,14 +1612,24 @@ static void
n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp,
char *fp, int count)
{
struct n_tty_data *ldata = tty->disc_data;
char flag = TTY_NORMAL;
while (count--) {
if (fp)
flag = *fp++;
if (likely(flag == TTY_NORMAL))
n_tty_receive_char_fast(tty, *cp++);
else
if (likely(flag == TTY_NORMAL)) {
unsigned char c = *cp++;
if (!test_bit(c, ldata->char_map))
n_tty_receive_char_fast(tty, c);
else if (n_tty_receive_char_special(tty, c) && count) {
if (fp)
flag = *fp++;
n_tty_receive_char_lnext(tty, *cp++, flag);
count--;
}
} else
n_tty_receive_char_flagged(tty, *cp++, flag);
}
}
......@@ -1634,6 +1647,15 @@ static void __receive_buf(struct tty_struct *tty, const unsigned char *cp,
else if (tty->closing && !L_EXTPROC(tty))
n_tty_receive_buf_closing(tty, cp, fp, count);
else {
if (ldata->lnext) {
char flag = TTY_NORMAL;
if (fp)
flag = *fp++;
n_tty_receive_char_lnext(tty, *cp++, flag);
count--;
}
if (!preops && !I_PARMRK(tty))
n_tty_receive_buf_fast(tty, cp, fp, count);
else
......
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