Hackers' Pub

Syntax	Description	Examples
`"` keyword `"`	Finds the string within quotes, including spaces. Case-insensitive. (Escape quotes inside with `\"`)	`"Hackers' Pub"`
`from:` handle	Finds content written by the specified user.	`from:hongminhee` `from:hongminhee@hollo.social`
`lang:` ISO 639-1	Finds content written in the specified language.	`lang:en`
`#` tag	Finds content with the specified tag. Case-insensitive.	`#HackersPub`
condition condition	Finds content that satisfies both conditions on either side of the space (logical AND).	`"Hackers' Pub" lang:en`
condition `OR` condition	Finds content that satisfies at least one of the conditions on either side of the OR operator (logical OR).	`#HackersPub OR "Hackers' Pub" lang:en`
`(` condition `)`	Combines the operators within the parentheses first.	`(#HackersPub OR "Hackers' Pub" OR "Hackers Pub") lang:en`

Jann Horn @jann@infosec.exchange

6/15/2025, 2:18:59 AM

Public

I never really thought about how processing of a single TCP ACK packet (tcp_clean_rtx_queue -> tcp_rtx_queue_unlink_and_free) might involve a bunch of main memory accesses for traversing the retransmit queue and freeing the SKBs in it and freeing the data pages that those SKBs point to... I guess in the optimal (and normal?) case the SKBs each cover something like 68 KiB, so the rbtree walk wouldn't be that long and most of the work would be freeing order-0 frag pages, which are pointed to by an array in the skb_shared_info, probably making the memory accesses for that somewhat more parallel?

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