to tune pthread mutex performance:
1. LIBPTHREAD_SPINLOOPS
If a pthread mutex is being locked by another thread, this environment
variable sets total number of spin loops before the current thread
sleeps in kernel, this saves a syscall overhead if the mutex will be
unlocked very soon (well written application code).
2. LIBPTHREAD_YIELDLOOPS
If a pthread mutex is being locked by other threads, this environment
variable sets total number of sched_yield() loops before the currrent
thread sleeps in kernel. if a pthread mutex is locked, the current thread
gives up cpu, but will not sleep in kernel, this means, current thread
does not set contention bit in mutex, but let lock owner to run again
if the owner is on kernel's run queue, and when lock owner unlocks the
mutex, it does not need to enter kernel and do lots of work to resume
mutex waiters, in some cases, this saves lots of syscall overheads for
mutex owner.
In my practice, sometimes LIBPTHREAD_YIELDLOOPS can massively improve performance
than LIBPTHREAD_SPINLOOPS, this depends on application. These two environments
are global to all pthread mutex, there is no interface to set them for each
pthread mutex, the default values are zero, this means spinning is turned off
by default.
is also implemented in glibc and is used by a number of existing
applications (mysql, firefox, etc).
This mutex type is a default mutex with the additional property that
it spins briefly when attempting to acquire a contested lock, doing
trylock operations in userland before entering the kernel to block if
eventually unsuccessful.
The expectation is that applications requesting this mutex type know
that the mutex is likely to be only held for very brief periods, so it
is faster to spin in userland and probably succeed in acquiring the
mutex, than to enter the kernel and sleep, only to be woken up almost
immediately. This can help significantly in certain cases when
pthread mutexes are heavily contended and held for brief durations
(such as mysql).
Spin up to 200 times before entering the kernel, which represents only
a few us on modern CPUs. No performance degradation was observed with
this value and it is sufficient to avoid a large performance drop in
mysql performance in the heavily contended pthread mutex case.
The libkse implementation is a NOP.
Reviewed by: jeff
MFC after: 3 days
This can only happen on 32-bit systems when you're reading
an uncompressed archive and the skip request is an exact
multiple of 4G (e.g., skipping a tar entry with an 8G body).
The symptom is that the read_ahead() ends up returning zero
bytes, and the extraction stops with a premature end-of-file.
Using '1' here is more correct anyway, as it allows read_ahead()
to function opportunistically and minimize copying.
MFC after: 5 days
kthread_add() takes the same parameters as the old kthread_create()
plus a pointer to a process structure, and adds a kernel thread
to that process.
kproc_kthread_add() takes the parameters for kthread_add,
plus a process name and a pointer to a pointer to a process instead of just
a pointer, and if the proc * is NULL, it creates the process to the
specifications required, before adding the thread to it.
All other old kthread_xxx() calls return, but act on (struct thread *)
instead of (struct proc *). One reason to change the name is so that
any old kernel modules that are lying around and expect kthread_create()
to make a process will not just accidentally link.
fix top to show kernel threads by their thread name in -SH mode
add a tdnam formatting option to ps to show thread names.
make all idle threads actual kthreads and put them into their own idled process.
make all interrupt threads kthreads and put them in an interd process
(mainly for aesthetic and accounting reasons)
rename proc 0 to be 'kernel' and it's swapper thread is now 'swapper'
man page fixes to follow.
on i386 and amd64 machines. The overall process is that /boot/pmbr lives
in the PMBR (similar to /boot/mbr for MBR disks) and is responsible for
locating and loading /boot/gptboot. /boot/gptboot is similar to /boot/boot
except that it groks GPT rather than MBR + bsdlabel. Unlike /boot/boot,
/boot/gptboot lives in its own dedicated GPT partition with a new
"FreeBSD boot" type. This partition does not have a fixed size in that
/boot/pmbr will load the entire partition into the lower 640k. However,
it is limited in that it can only be 545k. That's still a lot better than
the current 7.5k limit for boot2 on MBR. gptboot mostly acts just like
boot2 in that it reads /boot.config and loads up /boot/loader. Some more
details:
- Include uuid_equal() and uuid_is_nil() in libstand.
- Add a new 'boot' command to gpt(8) which makes a GPT disk bootable using
/boot/pmbr and /boot/gptboot. Note that the disk must have some free
space for the boot partition.
- This required exposing the backend of the 'add' function as a
gpt_add_part() function to the rest of gpt(8). 'boot' uses this to
create a boot partition if needed.
- Don't cripple cgbase() in the UFS boot code for /boot/gptboot so that
it can handle a filesystem > 1.5 TB.
- /boot/gptboot has a simple loader (gptldr) that doesn't do any I/O
unlike boot1 since /boot/pmbr loads all of gptboot up front. The
C portion of gptboot (gptboot.c) has been repocopied from boot2.c.
The primary changes are to parse the GPT to find a root filesystem
and to use 64-bit disk addresses. Currently gptboot assumes that the
first UFS partition on the disk is the / filesystem, but this algorithm
will likely be improved in the future.
- Teach the biosdisk driver in /boot/loader to understand GPT tables.
GPT partitions are identified as 'disk0pX:' (e.g. disk0p2:) which is
similar to the /dev names the kernel uses (e.g. /dev/ad0p2).
- Add a new "freebsd-boot" alias to g_part() for the new boot UUID.
MFC after: 1 month
Discussed with: marcel (some things might still change, but am committing
what I have so far)
a module was loaded might make the pathname inaccurate.
I wonder if an inode reference should be stored with the pathname
to allow a validity check?
Suggested by: rwatson@
threading library.
- Now that libpthread is a symlink, it's no longer possible
to link applications with libpthread and have libmap.conf(5)
select the desired threading library; applications will be
linked to the default threading library, libkse or libthr.
Remove an obsolete paragraph.
- Mention that improvements can be seen compared to libkse.
Reviewed by: deischen, davidxu
for kldstat(2).
This allows libdtrace to determine the exact file from which
a kernel module was loaded without having to guess.
The kldstat(2) API is versioned with the size of the
kld_file_stat structure, so this change creates version 2.
Add the pathname to the verbose output of kldstat(8) too.
MFC: 3 days
aligned, GCC 4.2.1 also generates code for sendudp() that assumes
this alignment. GCC 4.2.1 however doesn't 32-bit align wbuf, causing
the loader to crash due to an unaligned access of wbuf in sendudp()
when netbooting sparc64. Solve this by specifying wbuf as packed and
32-bit aligned, too. As for lastdata and readudp() this currently is
no issue when compiled with GCC 4.2.1, though give lastdata the same
treatment as wbuf for consistency and possibility of being affected
in the future. [1]
- Sprinkle const on a lookup table.
Reported by: marcel [1]
Submitted by: yongari [1]
Reviewed by: marcel [1]
MFC after: 5 days
test MK_INSTALLLIB, users can set WITHOUT_INSTALLLIB. The old
NO_INSTALLLIB is still supported as several makefiles set it.
- While here, fix an install when instructed not to install libs
(usr.bin/lex/lib/Makefile).
PR: bin/114200
Submitted by: Henrik Brix Andersen
This commit includes the following core components:
* sample configuration file for sensorsd
* rc(8) script and glue code for sensorsd(8)
* sysctl(3) doc fixes for CTL_HW tree
* sysctl(3) documentation for hardware sensors
* sysctl(8) documentation for hardware sensors
* support for the sensor structure for sysctl(8)
* rc.conf(5) documentation for starting sensorsd(8)
* sensor_attach(9) et al documentation
* /sys/kern/kern_sensors.c
o sensor_attach(9) API for drivers to register ksensors
o sensor_task_register(9) API for the update task
o sysctl(3) glue code
o hw.sensors shadow tree for sysctl(8) internal magic
* <sys/sensors.h>
* HW_SENSORS definition for <sys/sysctl.h>
* sensors display for systat(1), including documentation
* sensorsd(8) and all applicable documentation
The userland part of the framework is entirely source-code
compatible with OpenBSD 4.1, 4.2 and -current as of today.
All sensor readings can be viewed with `sysctl hw.sensors`,
monitored in semi-realtime with `systat -sensors` and also
logged with `sensorsd`.
Submitted by: Constantine A. Murenin <cnst@FreeBSD.org>
Sponsored by: Google Summer of Code 2007 (GSoC2007/cnst-sensors)
Mentored by: syrinx
Tested by: many
OKed by: kensmith
Obtained from: OpenBSD (parts)
for wide characters locales in the argument range >= 0x80 - they may
return false positives.
Example 1: for UTF-8 locale we currently have:
iswspace(0xA0)==1 and isspace(0xA0)==1
(because iswspace() and isspace() are the same code)
but must have
iswspace(0xA0)==1 and isspace(0xA0)==0
(because there is no such character and all others in the range
0x80..0xff for the UTF-8 locale, it keeps ASCII only in the single byte
range because our internal wchar_t representation for UTF-8 is UCS-4).
Example 2: for all wide character locales isalpha(arg) when arg > 0xFF may
return false positives (must be 0).
(because iswalpha() and isalpha() are the same code)
This change address this issue separating single byte and wide ctype
and also fix iswascii() (currently iswascii() is broken for
arguments > 0xFF).
This change is 100% binary compatible with old binaries.
Reviewied by: i18n@
