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Code Issues Releases Wiki Activity

ircd::ios: Torch any possible idiv in core epoll(2) instruction stream.

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This commit is contained in:
Jason Volk 2020-12-18 19:50:35 -08:00
parent c9b4fe6797
commit 7d1de2ded7
1 changed files with 17 additions and 8 deletions
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25
include/ircd/ios/epoll.h
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@ -51,28 +51,36 @@ ircd::ios::epoll_wait(int _epfd,
int _timeout)
noexcept
{
const bool peek
{
_timeout == 0
};
// Call elision tick counter.
thread_local uint64_t tick;
// Configured frequency to allow the call.
const uint64_t freq
{
empt::freq
};
const bool skip_tick
const bool skip
{
!freq || (uint64_t(empt::peek) % freq)
!freq || (tick < freq)
};
const bool peek
{
_timeout == 0
};
// Always allow blocking calls; only allow non-blocking calls which
// satisfy our conditions.
const bool call
{
!peek || !skip_tick
!peek || !skip
};
// Modify tick counter prior to call, while we have the line.
tick -= boolmask<decltype(tick)>(call) & tick;
tick += boolmask<decltype(tick)>(!call) & 0x01;
const int ret
{
call?
@ -94,8 +102,9 @@ noexcept
log::logf
{
log, ircd::log::DEBUG,
"EPOLL %5d peek:%lu skip:%lu call:%lu none:%lu result:%lu low:%lu med:%lu high:%lu stall:%lu",
"EPOLL %5d tick:%lu peek:%lu skip:%lu call:%lu none:%lu result:%lu low:%lu med:%lu high:%lu stall:%lu",
ret,
tick,
uint64_t(empt::peek),
uint64_t(empt::skip),
uint64_t(empt::call),