Hi Christian, > Hmm. Does ROOT not compress Byte_t members? Anyway, that is >50% For each class stored Version = 2bytes, counter 4 bytes, and at leas one byte of data. totally >= 7 bytes. > use Byte_t instead of UShort_t So you will save 1 byte which is 1/8 abot 12% not 50% Victor Christian Holm Christensen wrote: > > Hi Rene, > > On Thu, 17 Jan 2002 14:48:44 +0000 > Rene Brun <Rene.Brun@cern.ch> wrote > concerning "Re: [ROOT] reduction": > > Hi Christian, > > > > I must diasgree with you for at least 3 reasons. > > - ROOT compression will do better than your 1 byte data type. > > Hmm. Does ROOT not compress Byte_t members? Anyway, that is >50% > reduction; impressive. However, in memory, you still loose 1 byte per > object, which isn't a problem ofcourse :-) > > > - Very often , placing 1 Byte element in a class creates a misalignement > > problem and you run the risk to lose more space than you think to gain > > and also to lose time due to the misalignement > > Whoops, forgot that issue. But isn't that helped by the mechanism > where you put all members of one type in one continues array (or > something like that anyway). > > > - We cannot support all possible cases in the collection classes: > > a TObjArray with a wordcount of 1,2,4,8 bytes. > > Well, I didn't intend the collection counter to be of various sizes. > It was rather the objects that you put into the collection that could > use Byte_t instead of UShort_t. > > Yours, > > Christian Holm Christensen ------------------------------------------- > Address: Sankt Hansgade 23, 1. th. Phone: (+45) 35 35 96 91 > DK-2200 Copenhagen N Cell: (+45) 28 82 16 23 > Denmark Office: (+45) 353 25 305 > Email: cholm@nbi.dk Web: www.nbi.dk/~cholm -- Victor M. Perevoztchikov perev@bnl.gov perev@vxcern.cern.ch Brookhaven National Laboratory MS 510A PO Box 5000 Upton NY 11973-5000 tel office : 631-344-7894; fax 631-344-4206; home 631-345-2690
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