On Thu, Dec 18, 2014 at 02:29:51PM +0800, Chao Yu wrote: > Hi Changman, > > > -----Original Message----- > > From: Changman Lee [mailto:cm224.lee@xxxxxxxxx] > > Sent: Wednesday, December 17, 2014 11:09 PM > > To: Chao Yu > > Cc: Jaegeuk Kim; Changman Lee; linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > > Subject: Re: [f2fs-dev] [PATCH v2] f2fs: merge two uchar variable in struct node_info to reduce > > memory cost > > > > Hi Yu, > > > > This patch is effective only in 32 bit machine. In case of 64 bit > > machine, nat_entry will be aligned in 8 bytes due to pointer variable > > (i.e. struct list_head). So it can't get any benefit to reduce memory > > usage. In the case of node_info, however, it will be gain in terms of > > memory usage. > > Hence, I think it's not correct for commit log to describe this patch. > > > > Thanks for your review! :) > > AFFIK, in 64 bit machine, size of struct nat_entry is 40 bytes before this patch > apply, the reason is that our compiler will fill 3 bytes pads after flag as > nid's offset should align to type size of nid, and then fill 7 byte pads after > version as size of structure should align to 64 bits when the struct size is bigger > than 64 bits. > layout of struct nat_entry: > |-----8 bytes-----| > |list.next | > |list.prev | > |flag |nid | > |ino |blk_addr| > |version | > After we apply this patch, size of struct nat_entry will be reduced to 32 bytes. > Please correct me if I'm wrong. Hi, Sorry, you're right. I miscalculated. Thanks, > > Anyway, I agreed that commit log should be uptodate. > > Thanks, > Yu > > > Thanks, > > > > Reviewed-by: Changman Lee <cm224.lee@xxxxxxxxxxx> > > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
