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. 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
