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25e9d331dc
freebsd-skq/sys
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mjg 25e9d331dc Reduce contention on the proctree lock during heavy package build. 
There is a proctree -> allproc ordering established.

Most of the time it is either xlock -> xlock or slock -> slock.

On fork however there is a slock -> xlock pair which results in
pathological wait times due to threads keeping proctree held for
reading and all waiting on allproc. Switch this to xlock -> xlock.
Longer term fix would get rid of proctree in this place to begin with.
Right now it is necessary to walk the session/process group lists to
determine which id is free. The walk can be avoided e.g. with bitmaps.

The exit path used to have one place which dealt with allproc and
then with proctree. Move the allproc acquire into the section protected
by proctree. This reduces contention against threads waiting on proctree
in the fork codepath - the fork proctree holder does not have to wait
for allproc as often.

Finally, move tidhash manipulation outside of the area protected by
either of these locks. The removal from the hash was already unprotected.
There is no legitimate reason to look up thread ids for a process still
under construction.

This results in about 50% wait time reduction during -j 128 package build.
2018-02-20 02:18:30 +00:00
..
amd64 Rationalize license text on Linuxolator files 2018-02-16 15:00:14 +00:00
arm Add the MODULE_DEPEND()s needed so that the kernel linker can resolve all 2018-02-18 23:01:33 +00:00
arm64 Make v_wire_count a per-cpu counter(9) counter. This eliminates a 2018-02-12 22:53:00 +00:00
bsm sys: further adoption of SPDX licensing ID tags. 2017-11-20 19:43:44 +00:00
cam Report the number of remaining retries when we have an error that 2018-02-15 18:57:54 +00:00
cddl relax an assert in zfsctl_snapdir_lookup to match r323578 2018-02-19 08:55:22 +00:00
compat Implement list_safe_reset_next() function macro in the LinuxKPI. 2018-02-19 16:31:19 +00:00
conf Correct module symbol export handling 2018-02-16 15:38:02 +00:00
contrib Define CK_MD_TSO for the relevant arches (i386, amd64 and sparc64). 2018-02-16 17:50:06 +00:00
crypto ccp(4): Store IV in output buffer in GCM software fallback when requested 2018-01-27 07:41:31 +00:00
ddb Implement 'domainset', a cpuset based NUMA policy mechanism. This allows 2018-01-12 22:48:23 +00:00
dev Add more virtqueue getter methods 2018-02-19 19:31:18 +00:00
dts Add a skeleton Clock Manager for RPi2/3, and use that from pwm 2018-01-22 07:10:30 +00:00
fs {ext2|ufs}_readdir: Avoid setting negative ncookies. 2018-02-06 22:38:19 +00:00
gdb sys/gdb: further adoption of SPDX licensing ID tags. 2017-11-27 15:16:59 +00:00
geom Fix a memory leak introduced in r328426. 2018-02-16 15:41:03 +00:00
gnu bwn(4): txpid2g/txpid5g[lh] are not defined after sromrev 7; the default 2018-02-13 17:43:54 +00:00
i386 Rationalize license text on Linuxolator files 2018-02-16 15:00:14 +00:00
isa Add ISA PNP tables to ISA drivers. Fix a few incidental comments. 2018-01-29 00:22:30 +00:00
kern Reduce contention on the proctree lock during heavy package build. 2018-02-20 02:18:30 +00:00
kgssapi kgssapi: Remove trivial deadcode 2018-02-14 00:12:03 +00:00
libkern libkern: use nul for terminating char rather than 0 2018-02-13 19:17:48 +00:00
mips Make v_wire_count a per-cpu counter(9) counter. This eliminates a 2018-02-12 22:53:00 +00:00
modules Build at45d and mx25l SPI flash drivers as modules. 2018-02-19 01:49:19 +00:00
net BPF: Switch to 32 bit compatible mode only when thread is 32 bit 2018-01-25 12:13:41 +00:00
net80211 net80211: sanitize input for ieee80211_output() 2017-12-30 00:40:34 +00:00
netgraph ng_pppoe(8): add support for user-supplied Host-Uniq tag. 2018-02-14 21:17:44 +00:00
netinet Reinitialize IP header length after checksum calculation. It is used 2018-02-10 10:13:17 +00:00
netinet6 Update the MTU in affected routes when IPv6 RA changes the MTU 2018-02-12 19:49:20 +00:00
netipsec Remove unused variables and sysctl declaration. 2018-02-19 12:20:51 +00:00
netpfil Remove duplicate #include <netinet/ip_var.h>. 2018-02-07 19:12:05 +00:00
netsmb Unsign some values related to allocation. 2018-01-22 02:08:10 +00:00
nfs Modernize nfssvc(2) registartion. 2018-02-08 20:09:42 +00:00
nfsclient style: Remove remaining deprecated MALLOC/FREE macros 2018-01-25 22:25:13 +00:00
nfsserver sys: general adoption of SPDX licensing ID tags. 2017-11-27 15:23:17 +00:00
nlm Use syscall_helper_register() to register syscalls and initialize though 2018-02-10 01:09:22 +00:00
ofed Import the mthca kernel side infiniband driver from Linux 4.9 and fix 2018-02-13 17:04:34 +00:00
opencrypto Move per-operation data out of the csession structure. 2018-01-26 23:21:50 +00:00
powerpc Set internal error returns for OF_peer(), OF_child(), and OF_parent() to 2018-02-19 15:49:14 +00:00
riscv Make v_wire_count a per-cpu counter(9) counter. This eliminates a 2018-02-12 22:53:00 +00:00
rpc Do pass removing some write-only variables from the kernel. 2017-12-25 04:48:39 +00:00
security Reduce duplication in __mac_*_(file|link)(2) implementation. 2018-02-15 18:57:22 +00:00
sparc64 Make v_wire_count a per-cpu counter(9) counter. This eliminates a 2018-02-12 22:53:00 +00:00
sys Further parallelize the buffer cache. 2018-02-20 00:06:07 +00:00
teken sys: general adoption of SPDX licensing ID tags. 2017-11-27 15:23:17 +00:00
tests
tools Avoid using \$. It's an unknown escape sequence. Some awks warn about 2018-01-28 05:13:08 +00:00
ufs Do not free(9) uninitialized pointer. 2018-02-19 19:08:25 +00:00
vm Use the conventional name for an array of pages. 2018-02-16 15:38:22 +00:00
x86 Don't include DMAR map entry zone items in kernel dumps. 2018-02-18 16:03:50 +00:00
xdr sys: general adoption of SPDX licensing ID tags. 2017-11-27 15:23:17 +00:00
xen sys: general adoption of SPDX licensing ID tags. 2017-11-27 15:23:17 +00:00
Makefile Move sys/boot to stand. Fix all references to new location 2017-11-14 23:02:19 +00:00