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[107.215.223.229]) by smtp.gmail.com with ESMTPSA id cf22-20020a05622a401600b003a816011d51sm2647292qtb.38.2022.12.14.16.29.56 for (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Dec 2022 16:29:56 -0800 (PST) From: Bakul Shah Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3731.300.101.1.3\)) Date: Wed, 14 Dec 2022 16:29:45 -0800 References: <20221211200327.GC8801@mcvoy.com> <8F5B431B-3789-42C7-8E34-0B6A417B41CF@iitbombay.org> To: The Eunuchs Hysterical Society In-Reply-To: Message-Id: <4A770CCE-2BC9-4DA7-B3D7-71AF9A23F79E@iitbombay.org> X-Mailer: Apple Mail (2.3731.300.101.1.3) Message-ID-Hash: JDOAEBIJWW2MIRPHDFSU2IXDMHUPDITN X-Message-ID-Hash: JDOAEBIJWW2MIRPHDFSU2IXDMHUPDITN X-MailFrom: bakul@iitbombay.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; header-match-tuhs.tuhs.org-0; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: Clever code (was Re: Re: Stdin Redirect in Cu History/Alternatives? List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: On Dec 11, 2022, at 7:09 PM, Andrew Warkentin wrote: > > It's not necessarily true that microkernels are significantly slower. uKernels are usually quite fast as they do so little. What can be slow is emulating a Unix like OS on top due to context switches. For instance, a user process doing read() will have the following context switches: userProc->uK->FileSystem->uK->diskDriver->uk->FileSysem->uK->userProc or worse (I didn't account for a few things). Because of this even some uKernels run a few critical services + drivers in the supervisor mode. But overall slowdown of such a unix emulation will very much depend on the workload and also what kind of performance improvements you are willing to try in a complex kernel vs same services running in user mode. At present the linux kernel has about 31+ Million lines (accounting for all architectures, filesystems, device drivers etc.). The FreeBSD 13.x kernel is about 8.7M LoC (of which 44-45% are in device drivers). I only counted .c and .h files. In contract FreeBSD 2.2.2 kernel has ~554K LoC. This LoC growth is entirely understandable but I wonder how things may have turned out in an alternate universe of uKernel based designs....