From e60d27c4d8b33ba20896b76b6558f061bc6460ff Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Wed, 24 Jul 2013 08:29:56 -0400 Subject: [PATCH] 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: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/n_tty.c | 166 +++++++++++++++++++++++++++++----------------------- 1 file changed, 94 insertions(+), 72 deletions(-) diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 7358263..dd8ae0c 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -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 @@ handle_newline: kill_fasync(&tty->fasync, SIGIO, POLL_IN); if (waitqueue_active(&tty->read_wait)) wake_up_interruptible(&tty->read_wait); - return; + return 0; } } @@ -1389,43 +1390,36 @@ handle_newline: 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)) { - start_tty(tty); - process_echoes(tty); - } - if (L_ECHO(tty)) { - finish_erasing(ldata); - /* Record the column of first canon char. */ - if (ldata->canon_head == ldata->read_head) - echo_set_canon_col(ldata); - echo_char(c, tty); - commit_echoes(tty); - } - parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; - if (parmrk) - put_tty_queue(c, ldata); - put_tty_queue(c, ldata); - return; + if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) { + start_tty(tty); + process_echoes(tty); } + if (L_ECHO(tty)) { + finish_erasing(ldata); + /* Record the column of first canon char. */ + if (ldata->canon_head == ldata->read_head) + echo_set_canon_col(ldata); + echo_char(c, tty); + commit_echoes(tty); + } + parmrk = (c == (unsigned char) '\377' && I_PARMRK(tty)) ? 1 : 0; + if (parmrk) + put_tty_queue(c, ldata); + put_tty_queue(c, ldata); +} - 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 @@ -1433,33 +1427,19 @@ 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)) { - start_tty(tty); - process_echoes(tty); - } - if (L_ECHO(tty)) { - finish_erasing(ldata); - /* Record the column of first canon char. */ - if (ldata->canon_head == ldata->read_head) - echo_set_canon_col(ldata); - echo_char(c, tty); - commit_echoes(tty); - } - put_tty_queue(c, ldata); - return; + if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) { + start_tty(tty); + process_echoes(tty); } - - n_tty_receive_char_special(tty, c); + if (L_ECHO(tty)) { + finish_erasing(ldata); + /* Record the column of first canon char. */ + if (ldata->canon_head == ldata->read_head) + echo_set_canon_col(ldata); + echo_char(c, tty); + commit_echoes(tty); + } + put_tty_queue(c, ldata); } 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 -- 2.7.4