* Re: Feedback for fastselect and one-copy-pipe
2001-03-12 14:15 Feedback for fastselect and one-copy-pipe Ingo Oeser
2001-03-12 16:20 ` Mike Galbraith
@ 2001-03-12 16:42 ` Manfred Spraul
2001-03-12 18:12 ` kuznet
1 sibling, 1 reply; 12+ messages in thread
From: Manfred Spraul @ 2001-03-12 16:42 UTC (permalink / raw)
To: Ingo Oeser; +Cc: linux-kernel, mikeg
[-- Attachment #1: Type: text/plain, Size: 1418 bytes --]
Ingo Oeser wrote:
>
> Hi Manfred,
>
> I'm running your patches [1] with sucess for a while now.
>
> Did you get any feedback about problems regarding these patches?
>
No feedback yet.
> They seem to work for me, but there seems to be a memleak in
> 2.4.x (x: 0-2), which I'm chasing down.
>
You are right, there's a stupid bug in my poll patch:
p = kmalloc(PAGE_SIZE);
free_page((unsigned long)p);
This causes a memory leak for the slab control structures.
>
> [1] put on http://www.tu-chemnitz.de/~ioe/fastpipe.patch
>
That's davem's original
I rewrote it because I didn't like the nested loops. pipe_read() and
_write() were never easy to follow, and adding yet another set of goto &
for(;;) loops is IMHO a bad idea.
The main difference between my patch and davem's patch is that davem
uses zerocopy for exactly PAGE_SIZE sized transfers, I only use it for
transfers larger than PIPE_BUF.
<<<<< davem's patch
+ if (count >= PAGE_SIZE &&
+ !(filp->f_flags & O_NONBLOCK)) {
<<<<<<< my patch
+ if (count > PIPE_BUF && chars == PIPE_SIZE &&
+ (!(filp->f_flags & O_NONBLOCK))) {
<<<<<<<
On i386 PIPE_BUF is 4096, and thus
* davem's patch is faster, since glibc by default writes in 4096 byte
blocks
* davem's patch breaks apps that assume that write(,PIPE_BUF) after
poll(POLLOUT) never blocks, even for blocking pipes.
I've attached the newest versions of both patches.
--
Manfred
[-- Attachment #2: patch-kiopipe --]
[-- Type: text/plain, Size: 13059 bytes --]
// $Header$
// Kernel Version:
// VERSION = 2
// PATCHLEVEL = 4
// SUBLEVEL = 2
// EXTRAVERSION = -ac17
--- 2.4/fs/pipe.c Thu Feb 22 22:29:46 2001
+++ build-2.4/fs/pipe.c Mon Mar 12 16:02:48 2001
@@ -2,6 +2,9 @@
* linux/fs/pipe.c
*
* Copyright (C) 1991, 1992, 1999 Linus Torvalds
+ *
+ * Major pipe_read() and pipe_write() cleanup, kiobuf based
+ * single copy Copyright (C) 2001 Manfred Spraul
*/
#include <linux/mm.h>
@@ -10,6 +13,8 @@
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
+#include <linux/iobuf.h>
+#include <linux/highmem.h>
#include <asm/uaccess.h>
#include <asm/ioctls.h>
@@ -36,97 +41,149 @@
down(PIPE_SEM(*inode));
}
+struct pipe_pio {
+ int *pdone;
+ struct kiobuf iobuf;
+};
+
+static int
+pio_copy_to_user(struct kiobuf* iobuf, int offset, char* ubuf, int chars)
+{
+ int page_nr;
+ offset += iobuf->offset;
+ page_nr = offset/PAGE_SIZE;
+ offset %= PAGE_SIZE;
+ while(chars) {
+ int pcount = PAGE_SIZE-offset;
+ void *kaddr;
+ if (pcount > chars)
+ pcount = chars;
+ kaddr = kmap(iobuf->maplist[page_nr]);
+ if (copy_to_user(ubuf, kaddr+offset, pcount))
+ return 1;
+ kunmap(iobuf->maplist[page_nr]);
+ chars -= pcount;
+ ubuf += pcount;
+ offset = 0;
+ page_nr++;
+ }
+ return 0;
+}
+
static ssize_t
pipe_read(struct file *filp, char *buf, size_t count, loff_t *ppos)
{
struct inode *inode = filp->f_dentry->d_inode;
- ssize_t size, read, ret;
+ ssize_t read, ret;
- /* Seeks are not allowed on pipes. */
- ret = -ESPIPE;
- read = 0;
+ /* pread is not allowed on pipes. */
if (ppos != &filp->f_pos)
- goto out_nolock;
+ return -ESPIPE;
/* Always return 0 on null read. */
- ret = 0;
if (count == 0)
- goto out_nolock;
+ return 0;
- /* Get the pipe semaphore */
- ret = -ERESTARTSYS;
- if (down_interruptible(PIPE_SEM(*inode)))
- goto out_nolock;
+ down(PIPE_SEM(*inode));
- if (PIPE_EMPTY(*inode)) {
-do_more_read:
+ read = 0;
+ for (;;) {
+ /* read what data is available */
+ int chars = PIPE_LEN(*inode);
+ if (chars) {
+ char *pipebuf = PIPE_BASE(*inode);
+ int offset = PIPE_START(*inode);
+
+ if (chars > count)
+ chars = count;
+ ret = -EFAULT;
+ if(PIPE_IS_PIO(*inode)) {
+ struct pipe_pio* pio = ((struct pipe_pio*)pipebuf);
+ if(pio_copy_to_user(&pio->iobuf, offset, buf, chars))
+ goto out;
+
+ PIPE_LEN(*inode) -= chars;
+ if(!PIPE_LEN(*inode)) {
+ unmap_kiobuf(&pio->iobuf);
+ *pio->pdone = 1;
+ PIPE_IS_PIO(*inode) = 0;
+ PIPE_START(*inode) = 0;
+ } else {
+ PIPE_START(*inode) += chars;
+ }
+ } else {
+ if (chars > PIPE_SIZE-offset)
+ chars = PIPE_SIZE-offset;
+ if (copy_to_user(buf, pipebuf+offset, chars))
+ goto out;
+ PIPE_LEN(*inode) -= chars;
+ if (!PIPE_LEN(*inode)) {
+ /* Cache behaviour optimization */
+ PIPE_START(*inode) = 0;
+ } else {
+ PIPE_START(*inode) += chars;
+ PIPE_START(*inode) &= (PIPE_SIZE - 1);
+ }
+ }
+ read += chars;
+ count -= chars;
+ buf += chars;
+ }
ret = 0;
+ if (!count)
+ goto out;
+
+ /* Rare special case:
+ * The pipe buffer was really circular,
+ * the wrapped bytes must be read before sleeping.
+ */
+ if (PIPE_LEN(*inode))
+ continue;
+
+ /* Never sleep if no process has the pipe open
+ * for writing */
if (!PIPE_WRITERS(*inode))
goto out;
+ /* Never sleep if O_NONBLOCK is set */
ret = -EAGAIN;
if (filp->f_flags & O_NONBLOCK)
goto out;
- for (;;) {
- PIPE_WAITING_READERS(*inode)++;
- pipe_wait(inode);
- PIPE_WAITING_READERS(*inode)--;
- ret = -ERESTARTSYS;
- if (signal_pending(current))
- goto out;
+ /* optimization:
+ * pipe_read() should return even if only a single byte
+ * was read. (Posix Std. 6.4.1.2)
+ * But if another process is sleeping in pipe_write()
+ * then we wait for that data - it's invisible for user
+ * space programs.
+ */
+ if (PIPE_MORE_DATA_WAITING(*inode)) {
+ /*
+ * We know that we are going to sleep: signal
+ * writers synchronously that there is more
+ * room.
+ */
+ wake_up_interruptible_sync(PIPE_WAIT(*inode));
+ } else if (read) {
+ /* We know that there are no writers, no need
+ * for wake up.
+ */
ret = 0;
- if (!PIPE_EMPTY(*inode))
- break;
- if (!PIPE_WRITERS(*inode))
- goto out;
+ goto out;
}
- }
- /* Read what data is available. */
- ret = -EFAULT;
- while (count > 0 && (size = PIPE_LEN(*inode))) {
- char *pipebuf = PIPE_BASE(*inode) + PIPE_START(*inode);
- ssize_t chars = PIPE_MAX_RCHUNK(*inode);
-
- if (chars > count)
- chars = count;
- if (chars > size)
- chars = size;
-
- if (copy_to_user(buf, pipebuf, chars))
+ pipe_wait(inode);
+ ret = -ERESTARTSYS;
+ if (signal_pending(current))
goto out;
-
- read += chars;
- PIPE_START(*inode) += chars;
- PIPE_START(*inode) &= (PIPE_SIZE - 1);
- PIPE_LEN(*inode) -= chars;
- count -= chars;
- buf += chars;
}
- /* Cache behaviour optimization */
- if (!PIPE_LEN(*inode))
- PIPE_START(*inode) = 0;
-
- if (count && PIPE_WAITING_WRITERS(*inode) && !(filp->f_flags & O_NONBLOCK)) {
- /*
- * We know that we are going to sleep: signal
- * writers synchronously that there is more
- * room.
- */
- wake_up_interruptible_sync(PIPE_WAIT(*inode));
- if (!PIPE_EMPTY(*inode))
- BUG();
- goto do_more_read;
- }
+out:
/* Signal writers asynchronously that there is more room. */
- wake_up_interruptible(PIPE_WAIT(*inode));
+ if (read && !PIPE_IS_PIO(*inode))
+ wake_up_interruptible(PIPE_WAIT(*inode));
- ret = read;
-out:
up(PIPE_SEM(*inode));
-out_nolock:
if (read)
ret = read;
return ret;
@@ -137,113 +194,143 @@
{
struct inode *inode = filp->f_dentry->d_inode;
ssize_t free, written, ret;
+ int pio_done, do_wakeup;
- /* Seeks are not allowed on pipes. */
- ret = -ESPIPE;
- written = 0;
+ /* pwrite is not allowed on pipes. */
if (ppos != &filp->f_pos)
- goto out_nolock;
+ return -ESPIPE;
/* Null write succeeds. */
- ret = 0;
if (count == 0)
- goto out_nolock;
-
- ret = -ERESTARTSYS;
- if (down_interruptible(PIPE_SEM(*inode)))
- goto out_nolock;
+ return 0;
- /* No readers yields SIGPIPE. */
- if (!PIPE_READERS(*inode))
- goto sigpipe;
+ down(PIPE_SEM(*inode));
/* If count <= PIPE_BUF, we have to make it atomic. */
free = (count <= PIPE_BUF ? count : 1);
- /* Wait, or check for, available space. */
- if (filp->f_flags & O_NONBLOCK) {
- ret = -EAGAIN;
- if (PIPE_FREE(*inode) < free)
+ written = 0;
+ pio_done = 1;
+ do_wakeup = 0;
+ for(;;) {
+ /* No readers yields SIGPIPE. */
+ ret = -EPIPE;
+ if (!PIPE_READERS(*inode))
goto out;
- } else {
- while (PIPE_FREE(*inode) < free) {
- PIPE_WAITING_WRITERS(*inode)++;
- pipe_wait(inode);
- PIPE_WAITING_WRITERS(*inode)--;
- ret = -ERESTARTSYS;
- if (signal_pending(current))
- goto out;
- if (!PIPE_READERS(*inode))
- goto sigpipe;
- }
- }
-
- /* Copy into available space. */
- ret = -EFAULT;
- while (count > 0) {
- int space;
- char *pipebuf = PIPE_BASE(*inode) + PIPE_END(*inode);
- ssize_t chars = PIPE_MAX_WCHUNK(*inode);
-
- if ((space = PIPE_FREE(*inode)) != 0) {
- if (chars > count)
- chars = count;
- if (chars > space)
- chars = space;
-
- if (copy_from_user(pipebuf, buf, chars))
- goto out;
-
- written += chars;
- PIPE_LEN(*inode) += chars;
- count -= chars;
- buf += chars;
- space = PIPE_FREE(*inode);
- continue;
+ if(!PIPE_IS_PIO(*inode)) {
+ int chars;
+ /* Copy into available space. */
+ chars = PIPE_FREE(*inode);
+
+ /*
+ * Try zero-copy:
+ * - only possible if the normal pipe buffer
+ * is empty
+ * - only possible if we can block:
+ * a) O_NONBLOCK not set
+ * and
+ * b) request for more than PIPE_BUF bytes.
+ * No Unix version blocks in pipe write for
+ * <= PIPE_BUF bytes after poll() returned POLLOUT.
+ */
+ ret = -EFAULT;
+ if (count > PIPE_BUF && chars == PIPE_SIZE &&
+ (!(filp->f_flags & O_NONBLOCK))) {
+ struct pipe_pio* pio = (struct pipe_pio*)PIPE_BASE(*inode);
+ chars = KIO_MAX_ATOMIC_BYTES;
+ if (chars > count)
+ chars = count;
+ kiobuf_init(&pio->iobuf);
+ if(map_user_kiobuf(READ, &pio->iobuf, (unsigned long)buf, chars))
+ goto out;
+ PIPE_IS_PIO(*inode) = 1;
+ pio_done = 0;
+ pio->pdone = &pio_done;
+
+ written += chars;
+ PIPE_LEN(*inode) += chars;
+ count -= chars;
+ buf += chars;
+ do_wakeup = 1;
+ } else if (chars >= free) {
+ int offset;
+next_chunk:
+ offset = PIPE_END(*inode);
+
+ if (chars > count)
+ chars = count;
+ if (chars > PIPE_SIZE-offset)
+ chars = PIPE_SIZE-offset;
+ if (copy_from_user(PIPE_BASE(*inode)+offset, buf, chars))
+ goto out;
+
+ written += chars;
+ PIPE_LEN(*inode) += chars;
+ count -= chars;
+ buf += chars;
+ do_wakeup = 1;
+
+ if(!count)
+ break; /* DONE! */
+
+ /* special case: pipe buffer wrapped */
+ if(PIPE_LEN(*inode) != PIPE_SIZE) {
+ chars = PIPE_FREE(*inode);
+ goto next_chunk;
+ }
+ }
}
- ret = written;
+ ret = -EAGAIN;
if (filp->f_flags & O_NONBLOCK)
break;
- do {
+ /* Do not wakeup unless data was written, otherwise
+ * multiple writers can cause a wakeup storm
+ */
+ if(do_wakeup) {
/*
* Synchronous wake-up: it knows that this process
* is going to give up this CPU, so it doesnt have
* to do idle reschedules.
*/
wake_up_interruptible_sync(PIPE_WAIT(*inode));
- PIPE_WAITING_WRITERS(*inode)++;
- pipe_wait(inode);
- PIPE_WAITING_WRITERS(*inode)--;
- if (signal_pending(current))
- goto out;
- if (!PIPE_READERS(*inode))
- goto sigpipe;
- } while (!PIPE_FREE(*inode));
- ret = -EFAULT;
+ do_wakeup = 0;
+ }
+ if (count)
+ PIPE_MORE_DATA_WAITING(*inode)++;
+ pipe_wait(inode);
+ if (count)
+ PIPE_MORE_DATA_WAITING(*inode)--;
+ if (!count && pio_done)
+ break; /* DONE */
+ ret = -ERESTARTSYS;
+ if (signal_pending(current))
+ goto out;
}
-
- /* Signal readers asynchronously that there is more data. */
- wake_up_interruptible(PIPE_WAIT(*inode));
-
- inode->i_ctime = inode->i_mtime = CURRENT_TIME;
- mark_inode_dirty(inode);
-
out:
- up(PIPE_SEM(*inode));
-out_nolock:
- if (written)
- ret = written;
- return ret;
+ if(!pio_done) {
+ struct pipe_pio* pio = (struct pipe_pio*)PIPE_BASE(*inode);
+ PIPE_IS_PIO(*inode) = 0;
+ written -= PIPE_LEN(*inode);
+ PIPE_LEN(*inode) = 0;
+ unmap_kiobuf(&pio->iobuf);
+ wake_up_interruptible(PIPE_WAIT(*inode));
+ }
+ if (written) {
+ inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+ mark_inode_dirty(inode);
-sigpipe:
- if (written)
- goto out;
+ ret = written;
+ }
up(PIPE_SEM(*inode));
- send_sig(SIGPIPE, current, 0);
- return -EPIPE;
+ /* Signal readers asynchronously that there is more data. */
+ if(do_wakeup)
+ wake_up_interruptible(PIPE_WAIT(*inode));
+ if (ret == -EPIPE)
+ send_sig(SIGPIPE, current, 0);
+ return ret;
}
static loff_t
@@ -454,9 +541,10 @@
init_waitqueue_head(PIPE_WAIT(*inode));
PIPE_BASE(*inode) = (char*) page;
+ PIPE_IS_PIO(*inode) = 0;
PIPE_START(*inode) = PIPE_LEN(*inode) = 0;
PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 0;
- PIPE_WAITING_READERS(*inode) = PIPE_WAITING_WRITERS(*inode) = 0;
+ PIPE_MORE_DATA_WAITING(*inode) = 0;
PIPE_RCOUNTER(*inode) = PIPE_WCOUNTER(*inode) = 1;
return inode;
--- 2.4/include/linux/pipe_fs_i.h Wed Feb 7 20:02:07 2001
+++ build-2.4/include/linux/pipe_fs_i.h Mon Mar 12 16:02:48 2001
@@ -5,11 +5,11 @@
struct pipe_inode_info {
wait_queue_head_t wait;
char *base;
+ unsigned int is_pio;
unsigned int start;
unsigned int readers;
unsigned int writers;
- unsigned int waiting_readers;
- unsigned int waiting_writers;
+ unsigned int more_data;
unsigned int r_counter;
unsigned int w_counter;
};
@@ -21,12 +21,12 @@
#define PIPE_SEM(inode) (&(inode).i_sem)
#define PIPE_WAIT(inode) (&(inode).i_pipe->wait)
#define PIPE_BASE(inode) ((inode).i_pipe->base)
+#define PIPE_IS_PIO(inode) ((inode).i_pipe->is_pio)
#define PIPE_START(inode) ((inode).i_pipe->start)
#define PIPE_LEN(inode) ((inode).i_size)
#define PIPE_READERS(inode) ((inode).i_pipe->readers)
#define PIPE_WRITERS(inode) ((inode).i_pipe->writers)
-#define PIPE_WAITING_READERS(inode) ((inode).i_pipe->waiting_readers)
-#define PIPE_WAITING_WRITERS(inode) ((inode).i_pipe->waiting_writers)
+#define PIPE_MORE_DATA_WAITING(inode) ((inode).i_pipe->more_data)
#define PIPE_RCOUNTER(inode) ((inode).i_pipe->r_counter)
#define PIPE_WCOUNTER(inode) ((inode).i_pipe->w_counter)
@@ -34,8 +34,6 @@
#define PIPE_FULL(inode) (PIPE_LEN(inode) == PIPE_SIZE)
#define PIPE_FREE(inode) (PIPE_SIZE - PIPE_LEN(inode))
#define PIPE_END(inode) ((PIPE_START(inode) + PIPE_LEN(inode)) & (PIPE_SIZE-1))
-#define PIPE_MAX_RCHUNK(inode) (PIPE_SIZE - PIPE_START(inode))
-#define PIPE_MAX_WCHUNK(inode) (PIPE_SIZE - PIPE_END(inode))
/* Drop the inode semaphore and wait for a pipe event, atomically */
void pipe_wait(struct inode * inode);
[-- Attachment #3: patch-poll --]
[-- Type: text/plain, Size: 10035 bytes --]
// $Header$
// Kernel Version:
// VERSION = 2
// PATCHLEVEL = 4
// SUBLEVEL = 2
// EXTRAVERSION = -ac17
--- 2.4/fs/select.c Thu Feb 22 22:29:47 2001
+++ build-2.4/fs/select.c Mon Mar 12 17:01:45 2001
@@ -24,12 +24,6 @@
#define ROUND_UP(x,y) (((x)+(y)-1)/(y))
#define DEFAULT_POLLMASK (POLLIN | POLLOUT | POLLRDNORM | POLLWRNORM)
-struct poll_table_entry {
- struct file * filp;
- wait_queue_t wait;
- wait_queue_head_t * wait_address;
-};
-
struct poll_table_page {
struct poll_table_page * next;
struct poll_table_entry * entry;
@@ -52,11 +46,36 @@
* poll table.
*/
+/*
+ * Memory free and alloc took a significant part of the total
+ * sys_poll()/sys_select() execution time, thus I moved several
+ * structures on the stack:
+ * - sys_select has a 192 byte (enough for 256 fds) buffer on the stack.
+ * Please avoid selecting more than 5000 descriptors
+ * (kmalloc > 4096 bytes), and you can't select
+ * more than 170.000 fds (kmalloc > 128 kB)
+ * - sys_poll stores the first 24 file descriptors on the
+ * stack. If more than 24 descriptors are polled, then
+ * additional memory is allocated, but the first 24 descriptors
+ * always lie on the stack.
+ * - the poll table contains 8 wait queue entries. This means that no dynamic
+ * memory allocation is necessary for the wait queues if one of the first
+ * 8 file descriptors has new data.
+ * <manfred@colorfullife.com>
+ */
+
void poll_freewait(poll_table* pt)
{
struct poll_table_page * p = pt->table;
+ struct poll_table_entry * entry;
+ entry = pt->internal + pt->nr;
+ while(pt->nr > 0) {
+ pt->nr--;
+ entry--;
+ remove_wait_queue(entry->wait_address,&entry->wait);
+ fput(entry->filp);
+ }
while (p) {
- struct poll_table_entry * entry;
struct poll_table_page *old;
entry = p->entry;
@@ -67,39 +86,42 @@
} while (entry > p->entries);
old = p;
p = p->next;
- free_page((unsigned long) old);
+ kfree(old);
}
}
void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
{
- struct poll_table_page *table = p->table;
-
- if (!table || POLL_TABLE_FULL(table)) {
- struct poll_table_page *new_table;
+ struct poll_table_entry * entry;
- new_table = (struct poll_table_page *) __get_free_page(GFP_KERNEL);
- if (!new_table) {
- p->error = -ENOMEM;
- __set_current_state(TASK_RUNNING);
- return;
+ if(p->nr < POLL_TABLE_INTERNAL) {
+ entry = p->internal+p->nr++;
+ } else {
+ struct poll_table_page *table = p->table;
+
+ if (!table || POLL_TABLE_FULL(table)) {
+ struct poll_table_page *new_table;
+
+ new_table = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!new_table) {
+ p->error = -ENOMEM;
+ __set_current_state(TASK_RUNNING);
+ return;
+ }
+ new_table->entry = new_table->entries;
+ new_table->next = table;
+ p->table = new_table;
+ table = new_table;
}
- new_table->entry = new_table->entries;
- new_table->next = table;
- p->table = new_table;
- table = new_table;
- }
-
- /* Add a new entry */
- {
- struct poll_table_entry * entry = table->entry;
+ entry = table->entry;
table->entry = entry+1;
- get_file(filp);
- entry->filp = filp;
- entry->wait_address = wait_address;
- init_waitqueue_entry(&entry->wait, current);
- add_wait_queue(wait_address,&entry->wait);
}
+ /* Add a new entry */
+ get_file(filp);
+ entry->filp = filp;
+ entry->wait_address = wait_address;
+ init_waitqueue_entry(&entry->wait, current);
+ add_wait_queue(wait_address,&entry->wait);
}
#define __IN(fds, n) (fds->in + n)
@@ -233,14 +255,18 @@
return retval;
}
-static void *select_bits_alloc(int size)
+#define SELECT_INLINE_BYTES 32
+static inline void *select_bits_alloc(int size, void* internal)
{
+ if(size <= SELECT_INLINE_BYTES)
+ return internal;
return kmalloc(6 * size, GFP_KERNEL);
}
-static void select_bits_free(void *bits, int size)
+static inline void select_bits_free(void *bits, void* internal)
{
- kfree(bits);
+ if(bits != internal)
+ kfree(bits);
}
/*
@@ -254,10 +280,12 @@
#define MAX_SELECT_SECONDS \
((unsigned long) (MAX_SCHEDULE_TIMEOUT / HZ)-1)
+
asmlinkage long
sys_select(int n, fd_set *inp, fd_set *outp, fd_set *exp, struct timeval *tvp)
{
fd_set_bits fds;
+ char ibuf[6*SELECT_INLINE_BYTES];
char *bits;
long timeout;
int ret, size;
@@ -295,7 +323,7 @@
*/
ret = -ENOMEM;
size = FDS_BYTES(n);
- bits = select_bits_alloc(size);
+ bits = select_bits_alloc(size, ibuf);
if (!bits)
goto out_nofds;
fds.in = (unsigned long *) bits;
@@ -340,12 +368,18 @@
set_fd_set(n, exp, fds.res_ex);
out:
- select_bits_free(bits, size);
+ select_bits_free(bits, ibuf);
out_nofds:
return ret;
}
-#define POLLFD_PER_PAGE ((PAGE_SIZE) / sizeof(struct pollfd))
+struct poll_list {
+ struct poll_list *next;
+ int len;
+ struct pollfd entries[0];
+};
+
+#define POLLFD_PER_PAGE ((PAGE_SIZE-sizeof(struct poll_list)) / sizeof(struct pollfd))
static void do_pollfd(unsigned int num, struct pollfd * fdpage,
poll_table ** pwait, int *count)
@@ -379,39 +413,44 @@
}
}
-static int do_poll(unsigned int nfds, unsigned int nchunks, unsigned int nleft,
- struct pollfd *fds[], poll_table *wait, long timeout)
+static int do_poll(int nfds, struct poll_list *list,
+ poll_table *wait, long timeout)
{
- int count;
+ int count = 0;
poll_table* pt = wait;
-
+
for (;;) {
- unsigned int i;
-
+ struct poll_list* walk;
set_current_state(TASK_INTERRUPTIBLE);
- count = 0;
- for (i=0; i < nchunks; i++)
- do_pollfd(POLLFD_PER_PAGE, fds[i], &pt, &count);
- if (nleft)
- do_pollfd(nleft, fds[nchunks], &pt, &count);
+ walk = list;
+ while(walk != NULL) {
+ do_pollfd( walk->len, walk->entries, &pt, &count);
+ walk = walk->next;
+ }
pt = NULL;
if (count || !timeout || signal_pending(current))
break;
count = wait->error;
if (count)
break;
+
timeout = schedule_timeout(timeout);
}
current->state = TASK_RUNNING;
return count;
}
+#define INLINE_POLL_COUNT 24
asmlinkage long sys_poll(struct pollfd * ufds, unsigned int nfds, long timeout)
{
- int i, j, fdcount, err;
- struct pollfd **fds;
+ int fdcount, err;
+ unsigned int i;
+ struct poll_list *pollwalk;
+ struct {
+ struct poll_list head;
+ struct pollfd entries[INLINE_POLL_COUNT];
+ } polldata;
poll_table table, *wait;
- int nchunks, nleft;
/* Do a sanity check on nfds ... */
if (nfds > current->files->max_fds)
@@ -431,63 +470,65 @@
wait = NULL;
err = -ENOMEM;
- fds = NULL;
- if (nfds != 0) {
- fds = (struct pollfd **)kmalloc(
- (1 + (nfds - 1) / POLLFD_PER_PAGE) * sizeof(struct pollfd *),
- GFP_KERNEL);
- if (fds == NULL)
- goto out;
- }
+ polldata.head.next = NULL;
+ polldata.head.len = INLINE_POLL_COUNT;
+ if(nfds <= INLINE_POLL_COUNT)
+ polldata.head.len = nfds;
- nchunks = 0;
- nleft = nfds;
- while (nleft > POLLFD_PER_PAGE) { /* allocate complete PAGE_SIZE chunks */
- fds[nchunks] = (struct pollfd *)__get_free_page(GFP_KERNEL);
- if (fds[nchunks] == NULL)
+ pollwalk = &polldata.head;
+ i = nfds;
+ err = -ENOMEM;
+ goto start;
+ while(i!=0) {
+ struct poll_list *pp;
+ pp = kmalloc(sizeof(struct poll_list)+
+ sizeof(struct pollfd)*
+ (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i),
+ GFP_KERNEL);
+ if(pp==NULL)
goto out_fds;
- nchunks++;
- nleft -= POLLFD_PER_PAGE;
- }
- if (nleft) { /* allocate last PAGE_SIZE chunk, only nleft elements used */
- fds[nchunks] = (struct pollfd *)__get_free_page(GFP_KERNEL);
- if (fds[nchunks] == NULL)
+ pp->next=NULL;
+ pp->len = (i>POLLFD_PER_PAGE?POLLFD_PER_PAGE:i);
+ pollwalk->next = pp;
+ pollwalk = pp;
+start:
+ if (copy_from_user(pollwalk+1, ufds + nfds-i,
+ sizeof(struct pollfd)*pollwalk->len)) {
+ err = -EFAULT;
goto out_fds;
+ }
+ i -= pollwalk->len;
}
+
+ fdcount = do_poll(nfds, &polldata.head,
+ wait, timeout);
+ /* OK, now copy the revents fields back to user space. */
+ i = nfds;
+ pollwalk = &polldata.head;
err = -EFAULT;
- for (i=0; i < nchunks; i++)
- if (copy_from_user(fds[i], ufds + i*POLLFD_PER_PAGE, PAGE_SIZE))
- goto out_fds1;
- if (nleft) {
- if (copy_from_user(fds[nchunks], ufds + nchunks*POLLFD_PER_PAGE,
- nleft * sizeof(struct pollfd)))
- goto out_fds1;
+ while(pollwalk != NULL) {
+ struct pollfd * fds = pollwalk->entries;
+ int j;
+
+ for (j=0; j < pollwalk->len; j++, ufds++) {
+ if(__put_user(fds[j].revents, &ufds->revents))
+ goto out_fds;
+ }
+ i -= pollwalk->len;
+ pollwalk = pollwalk->next;
}
-
- fdcount = do_poll(nfds, nchunks, nleft, fds, wait, timeout);
-
- /* OK, now copy the revents fields back to user space. */
- for(i=0; i < nchunks; i++)
- for (j=0; j < POLLFD_PER_PAGE; j++, ufds++)
- __put_user((fds[i] + j)->revents, &ufds->revents);
- if (nleft)
- for (j=0; j < nleft; j++, ufds++)
- __put_user((fds[nchunks] + j)->revents, &ufds->revents);
-
err = fdcount;
if (!fdcount && signal_pending(current))
err = -EINTR;
-out_fds1:
- if (nleft)
- free_page((unsigned long)(fds[nchunks]));
out_fds:
- for (i=0; i < nchunks; i++)
- free_page((unsigned long)(fds[i]));
- if (nfds != 0)
- kfree(fds);
-out:
+ pollwalk = polldata.head.next;
+ while(pollwalk!=NULL) {
+ struct poll_list *pp = pollwalk->next;
+ kfree(pollwalk);
+ pollwalk = pp;
+ }
poll_freewait(&table);
return err;
}
--- 2.4/include/linux/poll.h Thu Jan 4 23:51:10 2001
+++ build-2.4/include/linux/poll.h Mon Mar 12 16:03:07 2001
@@ -12,9 +12,18 @@
struct poll_table_page;
+struct poll_table_entry {
+ struct file * filp;
+ wait_queue_t wait;
+ wait_queue_head_t * wait_address;
+};
+
+#define POLL_TABLE_INTERNAL 8
typedef struct poll_table_struct {
int error;
+ int nr;
struct poll_table_page * table;
+ struct poll_table_entry internal[POLL_TABLE_INTERNAL];
} poll_table;
extern void __pollwait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p);
@@ -28,6 +37,7 @@
static inline void poll_initwait(poll_table* pt)
{
pt->error = 0;
+ pt->nr = 0;
pt->table = NULL;
}
extern void poll_freewait(poll_table* pt);
^ permalink raw reply [flat|nested] 12+ messages in thread