Sujet : Re: Shutdown - 25 Years Later
De : robin_listas (at) *nospam* es.invalid (Carlos E.R.)
Groupes : comp.os.linux.miscDate : 25. Apr 2025, 22:20:31
Autres entêtes
Message-ID : <vtatdlxrcn.ln2@Telcontar.valinor>
References : 1 2 3 4 5 6 7 8 9 10 11 12 13 14
User-Agent : Mozilla Thunderbird
On 2025-04-24 02:23, Lawrence D'Oliveiro wrote:
On Wed, 23 Apr 2025 13:35:14 +0200, Carlos E.R. wrote:
On 2025-04-23 00:43, Lawrence D'Oliveiro wrote:
>
On Tue, 22 Apr 2025 10:35:48 +0200, Carlos E.R. wrote:
>
... I think it’s a dumb idea for drives to have their own cache.
>
Not at all. There is a huge speed improvement.
>
Not as fast as the OS can achieve by caching things in main RAM.
>
Remember, the on-drive cache is on the wrong side of an interface
(SATA, NVME etc) that is not designed to run at main RAM speeds.
Whereas the interface between CPU and main RAM is. That’s why on-drive
cache is a waste of time.
>
The on drive cache is on the right side to take advantage of the drive
own algorithms to move the head. The firmware takes decisions on where
sectors actually are, and what sectors to actually read or write and in
what order. The operating system doesn't have actual knowledge of the
internal layout of the disk platters and can not optimize for the actual
situation.
Yes it can. It uses algorithms I previously mentioned -- scatter read,
gather write, elevator seeking -- to assemble together large sequences of
I/O requests, larger than any on-drive cache can handle.
No, it can not. It does not have the access.
All the on-drive cache can offer is another potential point where things
can go wrong, leading to data loss.
-- Cheers, Carlos.
Re: Shutdown - 25 Years Later
Re: Shutdown - 25 Years Later