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[107.215.223.229]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-650edbc294dsm8155978a12.38.2024.05.18.18.51.07 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sat, 18 May 2024 18:51:08 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3774.600.62\)) In-Reply-To: <767E78C5-E6E7-4CB5-889D-B4E0E5FBA085@iitbombay.org> Date: Sat, 18 May 2024 18:50:57 -0700 Content-Transfer-Encoding: quoted-printable Message-Id: <80302C1F-99D7-4E5F-8656-2E7E67C40422@iitbombay.org> References: <20240514111032.2kotrrjjv772h5f4@illithid> <20240515164212.beswgy4h2nwvbdck@illithid> <8D556958-0C7F-43F3-8694-D7391E9D89DA@iitbombay.org> <20240519012114.GU9216@mcvoy.com> <767E78C5-E6E7-4CB5-889D-B4E0E5FBA085@iitbombay.org> To: Larry McVoy X-Mailer: Apple Mail (2.3774.600.62) Message-ID-Hash: WP4AK3ODQY64QQKHJLU2M34DSHP7B3CW X-Message-ID-Hash: WP4AK3ODQY64QQKHJLU2M34DSHP7B3CW X-MailFrom: bakul@iitbombay.org X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: The Unix Heritage Society mailing list X-Mailman-Version: 3.3.6b1 Precedence: list Subject: [TUHS] Re: If forking is bad, how about buffering? List-Id: The Unix Heritage Society mailing list Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: From: Bakul Shah via TUHS Reply-To: Bakul Shah X-Spam: Yes On May 18, 2024, at 6:40=E2=80=AFPM, Bakul Shah = wrote: >=20 > On May 18, 2024, at 6:21=E2=80=AFPM, Larry McVoy wrote: >>=20 >> On Sat, May 18, 2024 at 06:04:23PM -0700, Bakul Shah via TUHS wrote: >>> [1] This brings up a separate point: in a microkernel even a simple >>> thing like "foo | bar" would require a third process - a "pipe >>> service", to buffer up the output of foo! You may have reduced >>> the overhead of individual syscalls but you will have more of >>> cross-domain calls! >>=20 >> Do any micro kernels do address space to address space bcopy()? >=20 > mmapping the same page in two processes won't be hard but now > you have complicated cat (or some iolib)! And there are other issues. As Doug said in his original message in this thread: "And input buffering must never ingest data that the program will not eventually use." Consider something like this: (echo 1; echo 2)|(read; cat) This will print 2. Emulating this with mmaped buffers and copying will not be easy....