The tales of the cursed operating systems textbook!

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The Tale Of The Cursed Operating Systems Textbook @kiranb

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Grimoire “A book of magic spells and incantations”

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Chapter 1 it’s coming from INSIDE THE KERNEL

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OOM Killer qu’est-ce que c’est?

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/proc • a pseudo-ﬁle system about process information! • /proc/slabinfo (or `slabtop`)

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nsd nsd fork nsd fork nsd fork anon_vma anon_vma anon_vma anon_vma

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Chapter 2 ﬁNAGLEing

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hi! Here's headers! great! here’s the body!!! got it; thanks acknowledged!

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Nagle’s Algorithm for (i=0; i<100000; i++) write(socket, &buffer[i], 1); if you have only a few bytes to send, wait until - you have more to ﬁll a packet - or the server acknowledges all outstanding data - or you time out

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hi! Here's packet 1. ok I’m bored. here’s an ack. great! here’s the second packet!!! sweet! we’re done here.

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Chapter 3 oints [2015-05-12 23:05:47.9372] Caused by: com.mongodb.MongoException: BSONObj size: -286331154 (0xEEEEEEEE) is invalid. Size must be between 0 and 16793600(16MB) First element: oints: ? type=112

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Buffers! fsync! • `fsync` ﬂushes all pending writes to the database • and the optional `lock` parameter locks writes, so nothing else comes in.

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WHAT’S NEXT - concurrency!!! - scheduling ???