Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On Feb 1 10:50, Corinna Vinschen via Cygwin-patches wrote: > On Jan 28 15:33, Ken Brown via Cygwin-patches wrote: > > On 1/28/2021 11:07 AM, Corinna Vinschen via Cygwin-patches wrote: > > > One problem is that there are some applications in the wild which run > > > loops up to either sysconf(_SC_OPEN_MAX) or OPEN_MAX to handle open > > > descriptors. tcsh is one of them. It may slow done tcsh quite a bit > > > if the loop runs to 3200 now every time. > > > > I don't use tcsh. Is it easy to test this? > > I just checked the source. In the olden days, before the invention of > close-on-exec, tcsh closed all descriptors > 2 up to OPEN_MAX prior to > starting any executable. > > With close-on-exec this happens only at startup and after an error > occured. > > So testing should be easy: The tcsh startup may be noticably slower. I checked this right now and I don't see a noticable, i. .e, any, difference. Corinna
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On Jan 28 15:33, Ken Brown via Cygwin-patches wrote: > On 1/28/2021 11:07 AM, Corinna Vinschen via Cygwin-patches wrote: > > One problem is that there are some applications in the wild which run > > loops up to either sysconf(_SC_OPEN_MAX) or OPEN_MAX to handle open > > descriptors. tcsh is one of them. It may slow done tcsh quite a bit > > if the loop runs to 3200 now every time. > > I don't use tcsh. Is it easy to test this? I just checked the source. In the olden days, before the invention of close-on-exec, tcsh closed all descriptors > 2 up to OPEN_MAX prior to starting any executable. With close-on-exec this happens only at startup and after an error occured. So testing should be easy: The tcsh startup may be noticably slower. Corinna
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On Jan 29 14:23, Ken Brown via Cygwin-patches wrote: > On 1/28/2021 5:28 PM, Ken Brown via Cygwin-patches wrote: > > > ...ideally by adding a file include/cygwin/limits.h included by > > > include/limits.h, which defines __OPEN_MAX et al, as required. > > > > I'm not completely sure I follow. Do you mean include/cygwin/limits.h > > should contain > > > > #define __OPEN_MAX 3200 > > > > and include/limits.h should contain > > > > #define OPEN_MAX __OPEN_MAX ? > > > > For the sake of my education, could you explain the reason for this? > > Trying to answer my own question, I guess the idea is to hide implementation > details from viewers of limits.h. Is that right? Yes, that was the idea, kind of like a poor mans include/bits dir on Linux... > I took a stab at this and > am about to send a patchset. I'm not sure whether I made a reasonable > choice of "et al" in "__OPEN_MAX et al". Sorry, I didn't mean to imply you will have to do that right away. It was just a thought to move over more values in later patches. Corinna
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On 1/28/2021 5:28 PM, Ken Brown via Cygwin-patches wrote:
On 1/28/2021 11:13 AM, Corinna Vinschen via Cygwin-patches wrote:
On Jan 28 17:07, Corinna Vinschen via Cygwin-patches wrote:
On Jan 28 08:42, Ken Brown via Cygwin-patches wrote:
On 1/28/2021 5:20 AM, Corinna Vinschen via Cygwin-patches wrote:
On Jan 27 21:51, Ken Brown via Cygwin-patches wrote:
According to the Linux man page for getdtablesize(3), the latter is
supposed to return "the maximum number of files a process can have
open, one more than the largest possible value for a file descriptor."
The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
now return that.
Previously getdtablesize returned the current size of cygheap->fdtab,
Cygwin's internal file descriptor table. But this is a dynamically
growing table, and its current size does not reflect an actual limit
on the number of open files.
With this change, gnulib now reports that getdtablesize and
fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
corresponding gnulib modules will no longer use gnulib replacements on
Cygwin.
---
winsup/cygwin/syscalls.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 5da05b18a..1f16d54b9 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -2887,7 +2887,7 @@ setdtablesize (int size)
extern "C" int
getdtablesize ()
{
- return cygheap->fdtab.size;
+ return OPEN_MAX_MAX;
}
getdtablesize is used internally, too. After this change, the values
returned by sysconf and getrlimit should be revisited as well.
They will now return OPEN_MAX_MAX, as I think they should. The only
question in my mind is whether to simplify the code by removing the calls to
getdtablesize, something like this (untested):
But then again, what happens with OPEN_MAX in limits.h? Linux removed
it entirely. Given we have such a limit and it's not flexible as on
Linux, should we go ahead, drop OPEN_MAX_MAX entirely and define
OPEN_MAX as 3200?
...ideally by adding a file include/cygwin/limits.h included by
include/limits.h, which defines __OPEN_MAX et al, as required.
I'm not completely sure I follow. Do you mean include/cygwin/limits.h should
contain
#define __OPEN_MAX 3200
and include/limits.h should contain
#define OPEN_MAX __OPEN_MAX ?
For the sake of my education, could you explain the reason for this?
Trying to answer my own question, I guess the idea is to hide implementation
details from viewers of limits.h. Is that right? I took a stab at this and am
about to send a patchset. I'm not sure whether I made a reasonable choice of
"et al" in "__OPEN_MAX et al".
Ken
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On 1/28/2021 11:13 AM, Corinna Vinschen via Cygwin-patches wrote:
On Jan 28 17:07, Corinna Vinschen via Cygwin-patches wrote:
On Jan 28 08:42, Ken Brown via Cygwin-patches wrote:
On 1/28/2021 5:20 AM, Corinna Vinschen via Cygwin-patches wrote:
On Jan 27 21:51, Ken Brown via Cygwin-patches wrote:
According to the Linux man page for getdtablesize(3), the latter is
supposed to return "the maximum number of files a process can have
open, one more than the largest possible value for a file descriptor."
The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
now return that.
Previously getdtablesize returned the current size of cygheap->fdtab,
Cygwin's internal file descriptor table. But this is a dynamically
growing table, and its current size does not reflect an actual limit
on the number of open files.
With this change, gnulib now reports that getdtablesize and
fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
corresponding gnulib modules will no longer use gnulib replacements on
Cygwin.
---
winsup/cygwin/syscalls.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 5da05b18a..1f16d54b9 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -2887,7 +2887,7 @@ setdtablesize (int size)
extern "C" int
getdtablesize ()
{
- return cygheap->fdtab.size;
+ return OPEN_MAX_MAX;
}
getdtablesize is used internally, too. After this change, the values
returned by sysconf and getrlimit should be revisited as well.
They will now return OPEN_MAX_MAX, as I think they should. The only
question in my mind is whether to simplify the code by removing the calls to
getdtablesize, something like this (untested):
But then again, what happens with OPEN_MAX in limits.h? Linux removed
it entirely. Given we have such a limit and it's not flexible as on
Linux, should we go ahead, drop OPEN_MAX_MAX entirely and define
OPEN_MAX as 3200?
...ideally by adding a file include/cygwin/limits.h included by
include/limits.h, which defines __OPEN_MAX et al, as required.
I'm not completely sure I follow. Do you mean include/cygwin/limits.h should
contain
#define __OPEN_MAX 3200
and include/limits.h should contain
#define OPEN_MAX __OPEN_MAX ?
For the sake of my education, could you explain the reason for this?
Thanks.
Ken
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On 1/28/2021 11:07 AM, Corinna Vinschen via Cygwin-patches wrote:
On Jan 28 08:42, Ken Brown via Cygwin-patches wrote:
On 1/28/2021 5:20 AM, Corinna Vinschen via Cygwin-patches wrote:
On Jan 27 21:51, Ken Brown via Cygwin-patches wrote:
According to the Linux man page for getdtablesize(3), the latter is
supposed to return "the maximum number of files a process can have
open, one more than the largest possible value for a file descriptor."
The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
now return that.
Previously getdtablesize returned the current size of cygheap->fdtab,
Cygwin's internal file descriptor table. But this is a dynamically
growing table, and its current size does not reflect an actual limit
on the number of open files.
With this change, gnulib now reports that getdtablesize and
fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
corresponding gnulib modules will no longer use gnulib replacements on
Cygwin.
---
winsup/cygwin/syscalls.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 5da05b18a..1f16d54b9 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -2887,7 +2887,7 @@ setdtablesize (int size)
extern "C" int
getdtablesize ()
{
- return cygheap->fdtab.size;
+ return OPEN_MAX_MAX;
}
getdtablesize is used internally, too. After this change, the values
returned by sysconf and getrlimit should be revisited as well.
They will now return OPEN_MAX_MAX, as I think they should. The only
question in my mind is whether to simplify the code by removing the calls to
getdtablesize, something like this (untested):
But then again, what happens with OPEN_MAX in limits.h? Linux removed
it entirely. Given we have such a limit and it's not flexible as on
Linux, should we go ahead, drop OPEN_MAX_MAX entirely and define
OPEN_MAX as 3200?
Makes sense to me.
One problem is that there are some applications in the wild which run
loops up to either sysconf(_SC_OPEN_MAX) or OPEN_MAX to handle open
descriptors. tcsh is one of them. It may slow done tcsh quite a bit
if the loop runs to 3200 now every time.
I don't use tcsh. Is it easy to test this?
Ken
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On Jan 28 17:07, Corinna Vinschen via Cygwin-patches wrote:
> On Jan 28 08:42, Ken Brown via Cygwin-patches wrote:
> > On 1/28/2021 5:20 AM, Corinna Vinschen via Cygwin-patches wrote:
> > > On Jan 27 21:51, Ken Brown via Cygwin-patches wrote:
> > > > According to the Linux man page for getdtablesize(3), the latter is
> > > > supposed to return "the maximum number of files a process can have
> > > > open, one more than the largest possible value for a file descriptor."
> > > > The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
> > > > now return that.
> > > >
> > > > Previously getdtablesize returned the current size of cygheap->fdtab,
> > > > Cygwin's internal file descriptor table. But this is a dynamically
> > > > growing table, and its current size does not reflect an actual limit
> > > > on the number of open files.
> > > >
> > > > With this change, gnulib now reports that getdtablesize and
> > > > fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
> > > > corresponding gnulib modules will no longer use gnulib replacements on
> > > > Cygwin.
> > > > ---
> > > > winsup/cygwin/syscalls.cc | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
> > > > index 5da05b18a..1f16d54b9 100644
> > > > --- a/winsup/cygwin/syscalls.cc
> > > > +++ b/winsup/cygwin/syscalls.cc
> > > > @@ -2887,7 +2887,7 @@ setdtablesize (int size)
> > > > extern "C" int
> > > > getdtablesize ()
> > > > {
> > > > - return cygheap->fdtab.size;
> > > > + return OPEN_MAX_MAX;
> > > > }
> > >
> > > getdtablesize is used internally, too. After this change, the values
> > > returned by sysconf and getrlimit should be revisited as well.
> >
> > They will now return OPEN_MAX_MAX, as I think they should. The only
> > question in my mind is whether to simplify the code by removing the calls to
> > getdtablesize, something like this (untested):
>
> But then again, what happens with OPEN_MAX in limits.h? Linux removed
> it entirely. Given we have such a limit and it's not flexible as on
> Linux, should we go ahead, drop OPEN_MAX_MAX entirely and define
> OPEN_MAX as 3200?
...ideally by adding a file include/cygwin/limits.h included by
include/limits.h, which defines __OPEN_MAX et al, as required.
Corinna
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On Jan 28 08:42, Ken Brown via Cygwin-patches wrote:
> On 1/28/2021 5:20 AM, Corinna Vinschen via Cygwin-patches wrote:
> > On Jan 27 21:51, Ken Brown via Cygwin-patches wrote:
> > > According to the Linux man page for getdtablesize(3), the latter is
> > > supposed to return "the maximum number of files a process can have
> > > open, one more than the largest possible value for a file descriptor."
> > > The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
> > > now return that.
> > >
> > > Previously getdtablesize returned the current size of cygheap->fdtab,
> > > Cygwin's internal file descriptor table. But this is a dynamically
> > > growing table, and its current size does not reflect an actual limit
> > > on the number of open files.
> > >
> > > With this change, gnulib now reports that getdtablesize and
> > > fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
> > > corresponding gnulib modules will no longer use gnulib replacements on
> > > Cygwin.
> > > ---
> > > winsup/cygwin/syscalls.cc | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
> > > index 5da05b18a..1f16d54b9 100644
> > > --- a/winsup/cygwin/syscalls.cc
> > > +++ b/winsup/cygwin/syscalls.cc
> > > @@ -2887,7 +2887,7 @@ setdtablesize (int size)
> > > extern "C" int
> > > getdtablesize ()
> > > {
> > > - return cygheap->fdtab.size;
> > > + return OPEN_MAX_MAX;
> > > }
> >
> > getdtablesize is used internally, too. After this change, the values
> > returned by sysconf and getrlimit should be revisited as well.
>
> They will now return OPEN_MAX_MAX, as I think they should. The only
> question in my mind is whether to simplify the code by removing the calls to
> getdtablesize, something like this (untested):
But then again, what happens with OPEN_MAX in limits.h? Linux removed
it entirely. Given we have such a limit and it's not flexible as on
Linux, should we go ahead, drop OPEN_MAX_MAX entirely and define
OPEN_MAX as 3200?
One problem is that there are some applications in the wild which run
loops up to either sysconf(_SC_OPEN_MAX) or OPEN_MAX to handle open
descriptors. tcsh is one of them. It may slow done tcsh quite a bit
if the loop runs to 3200 now every time.
Corinna
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On 1/28/2021 5:20 AM, Corinna Vinschen via Cygwin-patches wrote:
On Jan 27 21:51, Ken Brown via Cygwin-patches wrote:
According to the Linux man page for getdtablesize(3), the latter is
supposed to return "the maximum number of files a process can have
open, one more than the largest possible value for a file descriptor."
The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
now return that.
Previously getdtablesize returned the current size of cygheap->fdtab,
Cygwin's internal file descriptor table. But this is a dynamically
growing table, and its current size does not reflect an actual limit
on the number of open files.
With this change, gnulib now reports that getdtablesize and
fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
corresponding gnulib modules will no longer use gnulib replacements on
Cygwin.
---
winsup/cygwin/syscalls.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 5da05b18a..1f16d54b9 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -2887,7 +2887,7 @@ setdtablesize (int size)
extern "C" int
getdtablesize ()
{
- return cygheap->fdtab.size;
+ return OPEN_MAX_MAX;
}
getdtablesize is used internally, too. After this change, the values
returned by sysconf and getrlimit should be revisited as well.
They will now return OPEN_MAX_MAX, as I think they should. The only question in
my mind is whether to simplify the code by removing the calls to getdtablesize,
something like this (untested):
diff --git a/winsup/cygwin/resource.cc b/winsup/cygwin/resource.cc
index 9e39d3a04..ac56acf8c 100644
--- a/winsup/cygwin/resource.cc
+++ b/winsup/cygwin/resource.cc
@@ -182,10 +182,7 @@ getrlimit (int resource, struct rlimit *rlp)
__get_rlimit_stack (rlp);
break;
case RLIMIT_NOFILE:
- rlp->rlim_cur = getdtablesize ();
- if (rlp->rlim_cur < OPEN_MAX)
- rlp->rlim_cur = OPEN_MAX;
- rlp->rlim_max = OPEN_MAX_MAX;
+ rlp->rlim_cur = rlp->rlim_max = OPEN_MAX_MAX;
break;
case RLIMIT_CORE:
rlp->rlim_cur = cygheap->rlim_core;
diff --git a/winsup/cygwin/sysconf.cc b/winsup/cygwin/sysconf.cc
index 001da96ad..d5d82bb4a 100644
--- a/winsup/cygwin/sysconf.cc
+++ b/winsup/cygwin/sysconf.cc
@@ -21,15 +21,6 @@ details. */
#include "cpuid.h"
#include "clock.h"
-static long
-get_open_max (int in)
-{
- long max = getdtablesize ();
- if (max < OPEN_MAX)
-max = OPEN_MAX;
- return max;
-}
-
static long
get_page_size (int in)
{
@@ -520,7 +511,7 @@ static struct
{cons, {c:CHILD_MAX}}, /* 1, _SC_CHILD_MAX */
{cons, {c:CLOCKS_PER_SEC}}, /* 2, _SC_CLK_TCK */
{cons, {c:NGROUPS_MAX}}, /* 3, _SC_NGROUPS_MAX */
- {func, {f:get_open_max}},/* 4, _SC_OPEN_MAX */
+ {cons, {c:OPEN_MAX_MAX}},/* 4, _SC_OPEN_MAX */
{cons, {c:_POSIX_JOB_CONTROL}}, /* 5, _SC_JOB_CONTROL */
{cons, {c:_POSIX_SAVED_IDS}},/* 6, _SC_SAVED_IDS */
{cons, {c:_POSIX_VERSION}}, /* 7, _SC_VERSION */
WDYT?
Ken
Re: [PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
On Jan 27 21:51, Ken Brown via Cygwin-patches wrote:
> According to the Linux man page for getdtablesize(3), the latter is
> supposed to return "the maximum number of files a process can have
> open, one more than the largest possible value for a file descriptor."
> The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
> now return that.
>
> Previously getdtablesize returned the current size of cygheap->fdtab,
> Cygwin's internal file descriptor table. But this is a dynamically
> growing table, and its current size does not reflect an actual limit
> on the number of open files.
>
> With this change, gnulib now reports that getdtablesize and
> fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
> corresponding gnulib modules will no longer use gnulib replacements on
> Cygwin.
> ---
> winsup/cygwin/syscalls.cc | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
> index 5da05b18a..1f16d54b9 100644
> --- a/winsup/cygwin/syscalls.cc
> +++ b/winsup/cygwin/syscalls.cc
> @@ -2887,7 +2887,7 @@ setdtablesize (int size)
> extern "C" int
> getdtablesize ()
> {
> - return cygheap->fdtab.size;
> + return OPEN_MAX_MAX;
> }
getdtablesize is used internally, too. After this change, the values
returned by sysconf and getrlimit should be revisited as well.
Thanks,
Corinna
[PATCH] Cygwin: getdtablesize: always return OPEN_MAX_MAX
According to the Linux man page for getdtablesize(3), the latter is
supposed to return "the maximum number of files a process can have
open, one more than the largest possible value for a file descriptor."
The constant OPEN_MAX_MAX is the only limit enforced by Cygwin, so we
now return that.
Previously getdtablesize returned the current size of cygheap->fdtab,
Cygwin's internal file descriptor table. But this is a dynamically
growing table, and its current size does not reflect an actual limit
on the number of open files.
With this change, gnulib now reports that getdtablesize and
fcntl(F_DUPFD) work on Cygwin. Packages like GNU tar that use the
corresponding gnulib modules will no longer use gnulib replacements on
Cygwin.
---
winsup/cygwin/syscalls.cc | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 5da05b18a..1f16d54b9 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -2887,7 +2887,7 @@ setdtablesize (int size)
extern "C" int
getdtablesize ()
{
- return cygheap->fdtab.size;
+ return OPEN_MAX_MAX;
}
extern "C" int
--
2.30.0
