Messages in this thread Patch in this message | | | Date | Tue, 14 Sep 2004 13:06:11 +0200 | From | Ingo Molnar <> | Subject | [patch] sched, tty: fix scheduling latencies in tty_io.c |
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the attached patch fixes long scheduling latencies in tty_read() and tty_write() caused by the BKL.
has been tested as part of the -VP patchset and the tty_read() side has also been tested in earlier -mm trees.
Ingo
the attached patch fixes long scheduling latencies in tty_read() and tty_write() caused by the BKL.
has been tested as part of the -VP patchset and the tty_read() side has also been tested in earlier -mm trees.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--- linux/drivers/char/tty_io.c.orig +++ linux/drivers/char/tty_io.c @@ -660,12 +660,10 @@ static ssize_t tty_read(struct file * fi if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags))) return -EIO; - lock_kernel(); if (tty->ldisc.read) i = (tty->ldisc.read)(tty,file,buf,count); else i = -EIO; - unlock_kernel(); if (i > 0) inode->i_atime = CURRENT_TIME; return i; @@ -688,17 +686,13 @@ static inline ssize_t do_tty_write( return -ERESTARTSYS; } if ( test_bit(TTY_NO_WRITE_SPLIT, &tty->flags) ) { - lock_kernel(); written = write(tty, file, buf, count); - unlock_kernel(); } else { for (;;) { unsigned long size = max((unsigned long)PAGE_SIZE*2, 16384UL); if (size > count) size = count; - lock_kernel(); ret = write(tty, file, buf, size); - unlock_kernel(); if (ret <= 0) break; written += ret;
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