Module Name: src
Committed By: jdolecek
Date: Thu Jun 25 14:22:19 UTC 2020
Modified Files:
src/sys/kern: sys_pipe.c
src/sys/sys: pipe.h
Log Message:
remove experimental direct pipe code (using uvm_loan()) I added in 2001 - it's
slower than the non-direct variant on MP systems, if anybody wants
to hack on this further it's available in Attic
To generate a diff of this commit:
cvs rdiff -u -r1.148 -r1.149 src/sys/kern/sys_pipe.c
cvs rdiff -u -r1.36 -r1.37 src/sys/sys/pipe.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/sys_pipe.c
diff -u src/sys/kern/sys_pipe.c:1.148 src/sys/kern/sys_pipe.c:1.149
--- src/sys/kern/sys_pipe.c:1.148 Fri Apr 26 17:24:23 2019
+++ src/sys/kern/sys_pipe.c Thu Jun 25 14:22:18 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: sys_pipe.c,v 1.148 2019/04/26 17:24:23 mlelstv Exp $ */
+/* $NetBSD: sys_pipe.c,v 1.149 2020/06/25 14:22:18 jdolecek Exp $ */
/*-
* Copyright (c) 2003, 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.148 2019/04/26 17:24:23 mlelstv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v 1.149 2020/06/25 14:22:18 jdolecek Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@@ -92,24 +92,6 @@ __KERNEL_RCSID(0, "$NetBSD: sys_pipe.c,v
#include <sys/atomic.h>
#include <sys/pipe.h>
-/*
- * Use this to disable direct I/O and decrease the code size:
- * #define PIPE_NODIRECT
- */
-
-/* XXX Disabled for now; rare hangs switching between direct/buffered */
-#define PIPE_NODIRECT
-
-#ifndef PIPE_NODIRECT
-#include <uvm/uvm.h>
-
-#if !defined(PMAP_DIRECT)
-# define PIPE_NODIRECT /* Direct map interface not available */
-#endif
-
-bool pipe_direct = true;
-#endif
-
static int pipe_read(file_t *, off_t *, struct uio *, kauth_cred_t, int);
static int pipe_write(file_t *, off_t *, struct uio *, kauth_cred_t, int);
static int pipe_close(file_t *);
@@ -159,19 +141,10 @@ static int pipe_create(struct pipe **, p
static int pipelock(struct pipe *, bool);
static inline void pipeunlock(struct pipe *);
static void pipeselwakeup(struct pipe *, struct pipe *, int);
-#ifndef PIPE_NODIRECT
-static int pipe_direct_write(file_t *, struct pipe *, struct uio *);
-#endif
static int pipespace(struct pipe *, int);
static int pipe_ctor(void *, void *, int);
static void pipe_dtor(void *, void *);
-#ifndef PIPE_NODIRECT
-static int pipe_loan_alloc(struct pipe *, int);
-static void pipe_loan_free(struct pipe *);
-static int pipe_direct_process_read(void *, size_t, void *);
-#endif /* PIPE_NODIRECT */
-
static pool_cache_t pipe_wr_cache;
static pool_cache_t pipe_rd_cache;
@@ -439,16 +412,6 @@ pipeselwakeup(struct pipe *selp, struct
fownsignal(sigp->pipe_pgid, SIGIO, code, band, selp);
}
-#ifndef PIPE_NODIRECT
-static int
-pipe_direct_process_read(void *va, size_t len, void *arg)
-{
- struct uio *uio = (struct uio *)arg;
-
- return uiomove(va, len, uio);
-}
-#endif
-
static int
pipe_read(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
int flags)
@@ -507,45 +470,6 @@ again:
continue;
}
-#ifndef PIPE_NODIRECT
- if ((rpipe->pipe_state & PIPE_DIRECTR) != 0) {
- struct pipemapping * const rmap = &rpipe->pipe_map;
- voff_t pgoff;
- u_int pgst, npages;
-
- /*
- * Direct copy, bypassing a kernel buffer.
- */
- KASSERT(rpipe->pipe_state & PIPE_DIRECTW);
-
- size = MIN(rmap->cnt, uio->uio_resid);
-
- if (size > 0) {
- KASSERT(size > 0);
- mutex_exit(lock);
-
- pgst = rmap->pos >> PAGE_SHIFT;
- pgoff = rmap->pos & PAGE_MASK;
- npages = (size + pgoff + PAGE_SIZE - 1) >> PAGE_SHIFT;
- KASSERTMSG(npages > 0 && (pgst + npages) <= rmap->npages, "npages %u pgst %u rmap->npages %u", npages, pgst, rmap->npages);
-
- error = uvm_direct_process(&rmap->pgs[pgst], npages,
- pgoff, size, pipe_direct_process_read, uio);
- mutex_enter(lock);
-
- nread += size;
- rmap->pos += size;
- rmap->cnt -= size;
- }
-
- if (rmap->cnt == 0) {
- rpipe->pipe_state &= ~PIPE_DIRECTR;
- cv_broadcast(&rpipe->pipe_wcv);
- }
-
- continue;
- }
-#endif
/*
* Break if some data was read.
*/
@@ -574,12 +498,6 @@ again:
*/
pipeunlock(rpipe);
- /*
- * Re-check to see if more direct writes are pending.
- */
- if ((rpipe->pipe_state & PIPE_DIRECTR) != 0)
- goto again;
-
#if 1 /* XXX (dsl) I'm sure these aren't needed here ... */
/*
* We want to read more, wake up select/poll.
@@ -634,189 +552,6 @@ unlocked_error:
return (error);
}
-#ifndef PIPE_NODIRECT
-/*
- * Allocate structure for loan transfer.
- */
-static int
-pipe_loan_alloc(struct pipe *wpipe, int npages)
-{
- struct pipemapping * const wmap = &wpipe->pipe_map;
-
- KASSERT(wmap->npages == 0);
-
- if (npages > wmap->maxpages) {
- pipe_loan_free(wpipe);
-
- wmap->pgs = kmem_alloc(npages * sizeof(struct vm_page *), KM_NOSLEEP);
- if (wmap->pgs == NULL)
- return ENOMEM;
- wmap->maxpages = npages;
- }
-
- wmap->npages = npages;
-
- return (0);
-}
-
-/*
- * Free resources allocated for loan transfer.
- */
-static void
-pipe_loan_free(struct pipe *wpipe)
-{
- struct pipemapping * const wmap = &wpipe->pipe_map;
-
- if (wmap->maxpages > 0) {
- kmem_free(wmap->pgs, wmap->maxpages * sizeof(struct vm_page *));
- wmap->pgs = NULL;
- wmap->maxpages = 0;
- }
-
- wmap->npages = 0;
- wmap->pos = 0;
- wmap->cnt = 0;
-}
-
-/*
- * NetBSD direct write, using uvm_loan() mechanism.
- * This implements the pipe buffer write mechanism. Note that only
- * a direct write OR a normal pipe write can be pending at any given time.
- * If there are any characters in the pipe buffer, the direct write will
- * be deferred until the receiving process grabs all of the bytes from
- * the pipe buffer. Then the direct mapping write is set-up.
- *
- * Called with the long-term pipe lock held.
- */
-static int
-pipe_direct_write(file_t *fp, struct pipe *wpipe, struct uio *uio)
-{
- struct pipemapping * const wmap = &wpipe->pipe_map;
- kmutex_t * const lock = wpipe->pipe_lock;
- vaddr_t bbase, base, bend;
- vsize_t blen, bcnt;
- int error, npages;
- voff_t bpos;
-
- KASSERT(mutex_owned(lock));
- KASSERT(wmap->cnt == 0);
-
- mutex_exit(lock);
-
- /*
- * Handle first PIPE_DIRECT_CHUNK bytes of buffer. Deal with buffers
- * not aligned to PAGE_SIZE.
- */
- bbase = (vaddr_t)uio->uio_iov->iov_base;
- base = trunc_page(bbase);
- bend = round_page(bbase + uio->uio_iov->iov_len);
- blen = bend - base;
- bpos = bbase - base;
-
- if (blen > PIPE_DIRECT_CHUNK) {
- blen = PIPE_DIRECT_CHUNK;
- bend = base + blen;
- bcnt = PIPE_DIRECT_CHUNK - bpos;
- } else {
- bcnt = uio->uio_iov->iov_len;
- }
- npages = atop(blen);
-
- KASSERT((wpipe->pipe_state & (PIPE_DIRECTW | PIPE_DIRECTR)) == 0);
- KASSERT(wmap->npages == 0);
-
- /* Make sure page array is big enough */
- error = pipe_loan_alloc(wpipe, npages);
- if (error) {
- mutex_enter(lock);
- return (error);
- }
-
- /* Loan the write buffer memory from writer process */
- error = uvm_loan(&uio->uio_vmspace->vm_map, base, blen,
- wmap->pgs, UVM_LOAN_TOPAGE);
- if (error) {
- pipe_loan_free(wpipe);
- mutex_enter(lock);
- return (ENOMEM); /* so that caller fallback to ordinary write */
- }
-
- /* Now we can put the pipe in direct write mode */
- wmap->pos = bpos;
- wmap->cnt = bcnt;
-
- /*
- * But before we can let someone do a direct read, we
- * have to wait until the pipe is drained. Release the
- * pipe lock while we wait.
- */
- mutex_enter(lock);
- wpipe->pipe_state |= PIPE_DIRECTW;
- pipeunlock(wpipe);
-
- while (error == 0 && wpipe->pipe_buffer.cnt > 0) {
- cv_broadcast(&wpipe->pipe_rcv);
- error = cv_wait_sig(&wpipe->pipe_wcv, lock);
- if (error == 0 && wpipe->pipe_state & PIPE_EOF)
- error = EPIPE;
- }
-
- /* Pipe is drained; next read will off the direct buffer */
- wpipe->pipe_state |= PIPE_DIRECTR;
-
- /* Wait until the reader is done */
- while (error == 0 && (wpipe->pipe_state & PIPE_DIRECTR)) {
- cv_broadcast(&wpipe->pipe_rcv);
- pipeselwakeup(wpipe, wpipe, POLL_IN);
- error = cv_wait_sig(&wpipe->pipe_wcv, lock);
- if (error == 0 && wpipe->pipe_state & PIPE_EOF)
- error = EPIPE;
- }
-
- /* Take pipe out of direct write mode */
- wpipe->pipe_state &= ~(PIPE_DIRECTW | PIPE_DIRECTR);
-
- /* Acquire the pipe lock and cleanup */
- (void)pipelock(wpipe, false);
-
- mutex_exit(lock);
- /* XXX what happens if the writer process exits without waiting for reader?
- * XXX FreeBSD does a clone in this case */
- uvm_unloan(wmap->pgs, npages, UVM_LOAN_TOPAGE);
- mutex_enter(lock);
-
- if (error) {
- pipeselwakeup(wpipe, wpipe, POLL_ERR);
-
- /*
- * If nothing was read from what we offered, return error
- * straight on. Otherwise update uio resid first. Caller
- * will deal with the error condition, returning short
- * write, error, or restarting the write(2) as appropriate.
- */
- if (wmap->cnt == bcnt) {
- wmap->cnt = 0;
- cv_broadcast(&wpipe->pipe_wcv);
- return (error);
- }
-
- bcnt -= wmap->cnt;
- }
-
- uio->uio_resid -= bcnt;
- /* uio_offset not updated, not set/used for write(2) */
- uio->uio_iov->iov_base = (char *)uio->uio_iov->iov_base + bcnt;
- uio->uio_iov->iov_len -= bcnt;
- if (uio->uio_iov->iov_len == 0) {
- uio->uio_iov++;
- uio->uio_iovcnt--;
- }
-
- wmap->cnt = 0;
- return (error);
-}
-#endif /* !PIPE_NODIRECT */
-
static int
pipe_write(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred,
int flags)
@@ -862,9 +597,6 @@ pipe_write(file_t *fp, off_t *offset, st
*/
if ((uio->uio_resid > PIPE_SIZE) &&
(nbigpipe < maxbigpipes) &&
-#ifndef PIPE_NODIRECT
- (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
-#endif
(bp->size <= PIPE_SIZE) && (bp->cnt == 0)) {
if (pipespace(wpipe, BIG_PIPE_SIZE) == 0)
@@ -874,55 +606,6 @@ pipe_write(file_t *fp, off_t *offset, st
while (uio->uio_resid) {
size_t space;
-#ifndef PIPE_NODIRECT
- /*
- * Pipe buffered writes cannot be coincidental with
- * direct writes. Also, only one direct write can be
- * in progress at any one time. We wait until the currently
- * executing direct write is completed before continuing.
- *
- * We break out if a signal occurs or the reader goes away.
- */
- while (error == 0 && wpipe->pipe_state & PIPE_DIRECTW) {
- cv_broadcast(&wpipe->pipe_rcv);
- pipeunlock(wpipe);
- error = cv_wait_sig(&wpipe->pipe_wcv, lock);
- (void)pipelock(wpipe, false);
- if (wpipe->pipe_state & PIPE_EOF)
- error = EPIPE;
- }
- if (error)
- break;
-
- /*
- * If the transfer is large, we can gain performance if
- * we do process-to-process copies directly.
- * If the write is non-blocking, we don't use the
- * direct write mechanism.
- *
- * The direct write mechanism will detect the reader going
- * away on us.
- */
- if ((uio->uio_iov->iov_len >= PIPE_MINDIRECT) &&
- (fp->f_flag & FNONBLOCK) == 0 &&
- pipe_direct) {
- error = pipe_direct_write(fp, wpipe, uio);
-
- /*
- * Break out if error occurred, unless it's ENOMEM.
- * ENOMEM means we failed to allocate some resources
- * for direct write, so we just fallback to ordinary
- * write. If the direct write was successful,
- * process rest of data via ordinary write.
- */
- if (error == 0)
- continue;
-
- if (error != ENOMEM)
- break;
- }
-#endif /* PIPE_NODIRECT */
-
space = bp->size - bp->cnt;
/* Writes of size <= PIPE_BUF must be atomic. */
@@ -1085,12 +768,7 @@ pipe_ioctl(file_t *fp, u_long cmd, void
case FIONREAD:
mutex_enter(lock);
-#ifndef PIPE_NODIRECT
- if (pipe->pipe_state & PIPE_DIRECTW)
- *(int *)data = pipe->pipe_map.cnt;
- else
-#endif
- *(int *)data = pipe->pipe_buffer.cnt;
+ *(int *)data = pipe->pipe_buffer.cnt;
mutex_exit(lock);
return (0);
@@ -1100,12 +778,7 @@ pipe_ioctl(file_t *fp, u_long cmd, void
pipe = pipe->pipe_peer;
if (pipe == NULL)
*(int *)data = 0;
-#ifndef PIPE_NODIRECT
- else if (pipe->pipe_state & PIPE_DIRECTW)
- *(int *)data = pipe->pipe_map.cnt;
- else
-#endif
- *(int *)data = pipe->pipe_buffer.cnt;
+ *(int *)data = pipe->pipe_buffer.cnt;
mutex_exit(lock);
return (0);
@@ -1116,16 +789,6 @@ pipe_ioctl(file_t *fp, u_long cmd, void
if (pipe == NULL)
*(int *)data = 0;
else
-#ifndef PIPE_NODIRECT
- /*
- * If we're in direct-mode, we don't really have a
- * send queue, and any other write will block. Thus
- * zero seems like the best answer.
- */
- if (pipe->pipe_state & PIPE_DIRECTW)
- *(int *)data = 0;
- else
-#endif
*(int *)data = pipe->pipe_buffer.size -
pipe->pipe_buffer.cnt;
mutex_exit(lock);
@@ -1156,9 +819,6 @@ pipe_poll(file_t *fp, int events)
if (events & (POLLIN | POLLRDNORM))
if ((rpipe->pipe_buffer.cnt > 0) ||
-#ifndef PIPE_NODIRECT
- (rpipe->pipe_state & PIPE_DIRECTR) ||
-#endif
(rpipe->pipe_state & PIPE_EOF))
revents |= events & (POLLIN | POLLRDNORM);
@@ -1169,9 +829,6 @@ pipe_poll(file_t *fp, int events)
else {
if (events & (POLLOUT | POLLWRNORM))
if ((wpipe->pipe_state & PIPE_EOF) || (
-#ifndef PIPE_NODIRECT
- (wpipe->pipe_state & PIPE_DIRECTW) == 0 &&
-#endif
(wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt) >= PIPE_BUF))
revents |= events & (POLLOUT | POLLWRNORM);
@@ -1266,10 +923,6 @@ pipe_free_kmem(struct pipe *pipe)
}
pipe->pipe_buffer.buffer = NULL;
}
-#ifndef PIPE_NODIRECT
- if (pipe->pipe_map.npages > 0)
- pipe_loan_free(pipe);
-#endif /* !PIPE_NODIRECT */
}
/*
@@ -1391,9 +1044,6 @@ filt_piperead(struct knote *kn, long hin
wpipe = rpipe->pipe_peer;
kn->kn_data = rpipe->pipe_buffer.cnt;
- if ((kn->kn_data == 0) && (rpipe->pipe_state & PIPE_DIRECTW))
- kn->kn_data = rpipe->pipe_map.cnt;
-
if ((rpipe->pipe_state & PIPE_EOF) ||
(wpipe == NULL) || (wpipe->pipe_state & PIPE_EOF)) {
kn->kn_flags |= EV_EOF;
@@ -1429,8 +1079,6 @@ filt_pipewrite(struct knote *kn, long hi
return (1);
}
kn->kn_data = wpipe->pipe_buffer.size - wpipe->pipe_buffer.cnt;
- if (wpipe->pipe_state & PIPE_DIRECTW)
- kn->kn_data = 0;
if ((hint & NOTE_SUBMIT) == 0) {
mutex_exit(rpipe->pipe_lock);
Index: src/sys/sys/pipe.h
diff -u src/sys/sys/pipe.h:1.36 src/sys/sys/pipe.h:1.37
--- src/sys/sys/pipe.h:1.36 Wed Aug 22 01:05:24 2018
+++ src/sys/sys/pipe.h Thu Jun 25 14:22:19 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: pipe.h,v 1.36 2018/08/22 01:05:24 msaitoh Exp $ */
+/* $NetBSD: pipe.h,v 1.37 2020/06/25 14:22:19 jdolecek Exp $ */
/*
* Copyright (c) 1996 John S. Dyson
@@ -73,24 +73,11 @@ struct pipebuf {
};
/*
- * Information to support direct transfers between processes for pipes.
- */
-struct pipemapping {
- vsize_t cnt; /* number of chars in buffer */
- voff_t pos; /* current position within page */
- u_int npages; /* how many pages available */
- u_int maxpages; /* how many pages allocated */
- struct vm_page **pgs; /* pointers to the pages */
-};
-
-/*
* Bits in pipe_state.
*/
#define PIPE_ASYNC 0x001 /* Async I/O */
#define PIPE_EOF 0x010 /* Pipe is in EOF condition */
#define PIPE_SIGNALR 0x020 /* Do selwakeup() on read(2) */
-#define PIPE_DIRECTW 0x040 /* Pipe in direct write mode setup */
-#define PIPE_DIRECTR 0x080 /* Pipe direct read request (setup complete) */
#define PIPE_LOCKFL 0x100 /* Process has exclusive access to
pointers/data. */
#define PIPE_LWANT 0x200 /* Process wants exclusive access to
@@ -108,7 +95,6 @@ struct pipe {
kcondvar_t pipe_draincv; /* cv for close */
kcondvar_t pipe_lkcv; /* locking */
struct pipebuf pipe_buffer; /* data storage */
- struct pipemapping pipe_map; /* pipe mapping for direct I/O */
struct selinfo pipe_sel; /* for compat with select */
struct timespec pipe_atime; /* time of last access */
struct timespec pipe_mtime; /* time of last modify */
