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Author Topic: low performance when decompress + chech crc/sha1 for merged sets  (Read 3311 times)

jrcmilanez

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Hello Roman, how are you?

When scanning the sets with decompress + chech crc/sha1 for merged sets, clrmamepro checks all required roms for parent and after all required roms for the clones. You can see this for some big sets like sc4slc and many others too.

If it´s a merged set, why not check only for the clone roms after check crc/sha1 for the parent roms?
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Roman

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That's not correct.

The Scanner->Hash & CHD->decompress + check crc and/or sha1 check is done when a (single) file is checked within a set.
So each rom checksum within a set is only checked once, no matter if they are split of fully merged.

So if it's slow on your system or you got the impression they get checked multiple times then one of the following may be the reason:

- You may use solid 7z archives...then of course it gets slow since it's in the nature of solid archives that it needs to unpacks files over and over again to reach the file it wants to check. Use zip format or not solid archives then.

- Or you additionally got Settings->Compressor->General->Test Archive (decompress to memory)(Scanner only) enabled...which does a full decompress to memory of the archive on its own....each time an archive is accessed. No real need to have that enabled....turn it off.

- unlikely today, but maybe your machine is slow...or the hd....your mentioned sc4slc is a very very small set (guess something around 3 or 4 MB fully merged) ....and on a rather decent machine a check of this set even with sha1 enabled should take less than a second.
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