Date: Thu, 23 Aug 2018 11:28:25 +0200 From: Sebastian Huber <sebastian.huber@embedded-brains.de> To: Eugene Grosbein <eugen@grosbein.net>, FreeBSD <freebsd-hackers@freebsd.org> Subject: Re: epoch(9) background information? Message-ID: <978ae736-89b9-6d83-e2a1-d2834ca8ae55@embedded-brains.de> In-Reply-To: <5B7E7804.4030907@grosbein.net> References: <db397431-2c4c-64de-634a-20f38ce6a60e@embedded-brains.de> <3bfedcc3-0dae-7979-2bd4-da83f2c67e87@embedded-brains.de> <5B7E7804.4030907@grosbein.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On 23/08/18 11:01, Eugene Grosbein wrote: > On 23.08.2018 15:39, Sebastian Huber wrote: > >> We used the FreeBSD network stack also on low-end targets >> (uni-processor) such as MCF548x ColdFire, Atmel SAM V71, SPARC LEON, >> etc. in current production environments (not legacy systems). The >> introduction of lock-free data structures (Concurrency Kit) and this >> epoch memory reclamation makes little sense on these targets (at least >> from my point of view). However, FreeBSD has still the SMP configurati= on >> option (sys/conf/options) which suggests that SMP is optional. Is a >> uni-processor system something which is considered by the FreeBSD >> community as a thing worth supporting or can I expect that this is an >> exotic environment which will get less and less well supported in the >> future? I just need some guidance so that I can better plan for future >> FreeBSD baseline updates. > FreeBSD as virtualized uniprocessor guest should be supported at full s= cale, > as well as embedded applications using single core x86 and non-x86 CPUs= . If something should be supported, then there must be also someone who=20 ensures that this is actually the case. I don't know the FreeBSD=20 community good enough to judge if there is sufficient=20 manpower/funding/interest for a well supported uni-processor FreeBSD.=20 From the commits it is clear that FreeBSD receives a lot of attention=20 from CDN providers such as Netflix and Limelight Networks. They probably=20 don't care about uni-processor system support at all. The use of=20 lock-free data structures (Concurrency Kit) and the epoch memory=20 reclamation are now a mandatory infrastructure. There is no FreeBSD=20 configuration option to avoid this. The Concurrency Kit in sys/contrib/ck has no explicit support for the=20 FreeBSD RISC-V and MIPS architectures. So, I guess the fall-back=20 sys/contrib/ck/include/gcc/ck_pr.h is used. The atomic support in=20 sys/contrib/ck partially duplicates/extends the general atomic support=20 of the FreeBSD kernel ATOMIC(9). To me it is a bit unclear what will be=20 the future direction in the FreeBSD kernel with respect to lock-free=20 data structures. --=20 Sebastian Huber, embedded brains GmbH Address : Dornierstr. 4, D-82178 Puchheim, Germany Phone : +49 89 189 47 41-16 Fax : +49 89 189 47 41-09 E-Mail : sebastian.huber@embedded-brains.de PGP : Public key available on request. Diese Nachricht ist keine gesch=C3=A4ftliche Mitteilung im Sinne des EHUG= .
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?978ae736-89b9-6d83-e2a1-d2834ca8ae55>