From mboxrd@z Thu Jan 1 00:00:00 1970 From: erik quanstrom Date: Sat, 7 Jun 2014 00:43:58 -0400 To: 9fans@9fans.net Message-ID: <4ec94de4f9e0723c6b493e9ceadc98c7@brasstown.quanstro.net> In-Reply-To: <6DB43D16-3A34-47FF-9E99-50BF09B2AA63@fb.com> References: <6DB43D16-3A34-47FF-9E99-50BF09B2AA63@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Subject: Re: [9fans] advanced core Linux kernel features not in plan9 Topicbox-Message-UUID: f6f87442-ead8-11e9-9d60-3106f5b1d025 > I was curious to know which core features of the Linux kernel are not implemented > in the plan9 kernel. By core I mean that I know plan9 does not have all the drivers, > filesystems, buses, etc Linux has, but it has many of its core > features (virtual memory, paging, swapping, demand loading, copy on write, etc), > and even more. on a good day with the right kernel you may get paging with plan 9, but never swapping. i've turned it off in my kernels, and it's not coming back. it's hard to use with multiple page sizes, and as charles notes, devices are either big enough to not need it, or too small to have anything to page out to. > For instance I was not able to find any code related to the buffer cache Linux has. > If you open a big file in a plan9 process, then close it, and later you open it again, > will you pay the IO again? Or is it cached somewhere? there is no buffer cache in plan 9. file servers do cache, but they are typically not on the same box, so it should be clear why there is no buffer cache. - erik