Re: [PATCH v2 05/10] compat/posix: introduce writev(3p) wrapper
- From
brian m. carlson <sandals@crustytoothpaste.net>
- Date
- Mar 5, 2026, 22:22 UTC
- Message-ID
- <aaoCNUY3XVyFaDcu@fruit.crustytoothpaste.net>
- In-Reply-To
- <7e8b51d1-382d-47f8-be71-74e76f0c9888@kdbg.org>
On 2026-03-05 at 06:39:13, Johannes Sixt wrote:
Show 6 quoted lines
> Please don't. The use of writev may mislead you to depend on guarantees > that a kernel implementation of writev can provide, but a compat/ > implementation cannot. (For example, I read something about "the file > pointer shall be unchanged" in the case of errors.) Please use simple > and stupid functions (write). I highly doubt that you can squeeze out a > noticable performance improvement with writev.
I have Rust code that does show a substantial performance improvement with writev and I use it for a very similar purpose (printing the size before a packet of data).
I am okay with slightly loosening the guarantees to support our compat implementation if that's what we need to do.
-- brian m. carlson (they/them) Toronto, Ontario, CA