1 / 10

pipe file

제 32 강 : pipe file. pipe file. grep | who. write_count. 0. Data. PIPSIZ. read_count. user per process. (system) file table. inode table. u-ofile. inode. fd. 0 1 2 3 4. device. offset. dev_tab. i_size. f_offset.

santiago-martin
Download Presentation

pipe file

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 제32강 : pipe file pipe file

  2. grep | who write_count 0 Data PIPSIZ read_count

  3. userper process (system) file table inode table u-ofile inode fd 0 1 2 3 4 device offset dev_tab i_size f_offset

  4. 16 bit (64 KB) for (offset, size) is too small for regular files userper process (system) file table inode table u-ofile inode fd 0 1 2 3 4 device offset dev_tab i_size0 i_size1 f_offset [0] f_offset [1]

  5. 16 bit (64 KB) for (offset, size) is too small for regular files But 16 bit is enough for pipe file (size, offset) Use 2nd word for other purpose userper process (system) file table inode table u-ofile inode fd 0 1 2 3 4 Pipe file 4096 Bytes offset PIPSIZ (7846, 7715) i_size0 i_size1 f_offset [0] f_offset [1] write count read_count (count MOD PIPSIZ) (count MOD PIPSIZ)

  6. 7758: readp(fp) 7759: int *fp; 7760: { 7761: register *rp, *ip; 7763: rp = fp; 7764: ip = rp->f_inode; 7765: loop: 7768: plock(ip); 7772: if(rp->f_offset[1] == ip->i_size1) { 7773: if(rp->f_offset[1] != 0) { 7774: rp->f_offset[1] = 0; 7775: ip->i_size1 = 0; 7776: if(ip->i_mode&IWRITE) { 7777: ip->i_mode =& ~IWRITE; 7778: wakeup(ip+1); 7779: } 7780: } 7781: 7786: prele(ip); 7787: if(ip->i_count < 2) 7788: return; 7789: ip->i_mode =| IREAD; 7790: sleep(ip+2, PPIPE); 7791: goto loop; 7792: } 7795: u.u_offset[0] = 0; 7796: u.u_offset[1] = rp->f_offset[1]; 7797: readi(ip); 7798: rp->f_offset[1] = u.u_offset[1]; 7799: prele(ip); 7800: } 7805: writep(fp) 7806: { 7807: register *rp, *ip, c; 7809: rp = fp; 7810: ip = rp->f_inode; 7811: c = u.u_count; 7812: loop: 7815: plock(ip); 7816: if(c == 0) { 7817: prele(ip); 7818: u.u_count = 0; 7819: return; 7820: } 7825: if(ip->i_count < 2) { 7826: prele(ip); 7827: u.u_error = EPIPE; 7828: psignal(u.u_procp, SIGPIPE); 7829: return; 7830: } 7835: if(ip->i_size1 == PIPSIZ) { 7836: ip->i_mode =| IWRITE; 7837: prele(ip); 7838: sleep(ip+1, PPIPE); 7839: goto loop; 7840: } 7844: u.u_offset[0] = 0; 7845: u.u_offset[1] = ip->i_size1; 7846: u.u_count = min(c, PIPSIZ-u.u_offset[1]); 7847: c =- u.u_count; 7848: writei(ip); 7849: prele(ip); 7850: if(ip->i_mode&IREAD) { 7851: ip->i_mode =& ~IREAD; 7852: wakeup(ip+2); 7853: } 7854: goto loop; 7855: }

  7. write_count i_size1 0 Data PIPSIZ read_count f_offset[1] Also alternate use of i_mode : i_mode = IWRITE (writer is blocked) or IREAD(reader is blocked) i_size1: Write Counter f_offset[1]: Read Counter i_mode: Lock pipe file

  8. 7758: readp(fp) 7759: int *fp; 7760: { 7761: register *rp, *ip; 7763: rp = fp; 7764: ip = rp->f_inode; 7765: loop: 7768: plock(ip); 7772: if(rp->f_offset[1] == ip->i_size1) { 7773: if(rp->f_offset[1] != 0) { 7774: rp->f_offset[1] = 0; 7775: ip->i_size1 = 0; 7776: if(ip->i_mode&IWRITE) { 7777: ip->i_mode =& ~IWRITE; 7778: wakeup(ip+1); 7779: } 7780: } 7781: 7786: prele(ip); 7787: if(ip->i_count < 2) 7788: return; 7789: ip->i_mode =| IREAD; 7790: sleep(ip+2, PPIPE); 7791: goto loop; 7792: } 7795: u.u_offset[0] = 0; 7796: u.u_offset[1] = rp->f_offset[1]; 7797: readi(ip); 7798: rp->f_offset[1] = u.u_offset[1]; 7799: prele(ip); 7800: } 7758 (21-1) If reader’s counter reaches writer’s counter reader must sleep reset both counters to zero i_size1: Write Counter f_offset[1]: Read Counter i_mode: Lock pipe file After read-pipe is complete, update f_offset[1]

  9. 7805: writep(fp) 7806: { 7807: register *rp, *ip, c; 7809: rp = fp; 7810: ip = rp->f_inode; 7811: c = u.u_count; 7812: loop: 7815: plock(ip); 7816: if(c == 0) { 7817: prele(ip); 7818: u.u_count = 0; 7819: return; 7820: } 7825: if(ip->i_count < 2) { 7826: prele(ip); 7827: u.u_error = EPIPE; 7828: psignal(u.u_procp, SIGPIPE); 7829: return; 7830: } 7835: if(ip->i_size1 == PIPSIZ) { 7836: ip->i_mode =| IWRITE; 7837: prele(ip); 7838: sleep(ip+1, PPIPE); 7839: goto loop; 7840: } 7844: u.u_offset[0] = 0; 7845: u.u_offset[1] = ip->i_size1; 7846: u.u_count = min(c, PIPSIZ-u.u_offset[1]); 7847: c =- u.u_count; 7848: writei(ip); 7849: prele(ip); 7850: if(ip->i_mode&IREAD) { 7851: ip->i_mode =& ~IREAD; 7852: wakeup(ip+2); 7853: } 7854: goto loop; 7855: } 7800 (21-1) i_size1: Write Counter f_offset[1]: Read Counter i_mode: Lock pipe file If writer’s counter reaches max (pipe size) writer must sleep ( PIPSIZ – i_size1) PIPSIZ Data c= u.u_count /* amount of data */ After write-to-pipe is complete, writei() updates the size of pipe file  writei() updates i_size1

  10. IPC • Group of system calls (kernel service) for data exchange synchronization between different processes • Here, for pipe IPC – kernel support: • moved data between processes • Synchronized processes (block/wakeup) • Other IPC examples • pipe socket signal …. • Why so many? • Varying data size, synchronization requirements • (such as frequency, speed …..)

More Related