[parisc-linux] scatterlist (de-)construction
Grant Grundler
grundler@cup.hp.com
Fri, 27 Oct 2000 13:37:34 -0700 (PDT)
Dave,
The sg_list's I'm seeing for a simple "dd .. bs=64K" aren't
assembled very nicely. I have two issues with scatterlists:
o why are list entries in 1K sizes instead of NBPG sizes?
o Why are "blocks" *within* the same kernel page "badly" ordered?
I have to confess I have only spent an hour or so reviewing code
and documents for scatter-gather. I'm doing more but thought you
might off-hand know where to look. If these are architecture defined
behaviors, I can fix those.
I've been trying to implement sane/simple coalescing code for one
of the parisc-linux I/O MMU's (sba_iommu.c) and finding the input
scatterlist I have to work with sucks. I've appended the console
output with my debugging info. The algorithm currently attempts
to prepend or append adjacent entries in the scatterlist.
It would be nice if we only had to check the append case.
(Ref http://puffin.external.hp.com/cvs/linux/arch/parisc/kernel/sba_iommu.c)
FYI, parisc-linux is currently based on 2.4.0-test6.
The plan is to merge to something more recent after we cut
a "stable" version in the next week or two. I mention this
in case any work was done since -test6 was posted.
thanks,
grant
ps. I'm also ok with this getting forwarded to l-k though
I'm not subscribed.
[ notes:
xx,xx address,length pair
xx,xx+yy,yy checking "current" chunk (xx) + "current" sglist entry (yy)
(xx,xx) addr,len "chunk" parameters passed to sba_map_single()
when algorithm can't safely either prepend or append the
"current" scatterlist element to the "chunk".
__FUNCTION__ is *broken* for our toolchain and it look like a
generic gcc bug in the current gcc developement tree. The "()"
are supposed to have function names in front of them.
Magic decoder:
() START 64 entries sba_map_sg() entry poiny
() DONE 17 mappings sba_map_sg() exit
() START 64 entries, dfd7a800,400 sba_unmap_sg() entry w/first pair
() DONE (nents 47) sba_unmap_sg() exit (after unmapping 17 entries)
]
gggC3000:~# dd if=/dev/sda1 of=/dev/null bs=64k count=5
() START 64 entries
dfd7a800,400+dfd7ac00,400 dfd7a800,800+dfd7a000,400 (dfd7a800, 800)
dfd7a000,400+dfd7a400,400 dfd7a000,800+df6ba000,400 (dfd7a000, 800)
df6ba000,400+df6ba400,400 df6ba000,800+df6ba800,400 df6ba000,c00+df6bac00,400 df6ba000,1000+df6b9000,400 (df6ba000, 1000)
df6b9000,400+df6b9400,400 df6b9000,800+df6b9800,400 df6b9000,c00+df6b9c00,400 df6b9000,1000+df6b8000,400 (df6b9000, 1000)
df6b8000,400+df6b8400,400 df6b8000,800+df6b8800,400 df6b8000,c00+df6b8c00,400 df6b8000,1000+df6b7000,400 (df6b8000, 1000)
df6b7000,400+df6b7400,400 df6b7000,800+df6b7800,400 df6b7000,c00+df6b7c00,400 df6b7000,1000+df6b6000,400 (df6b7000, 1000)
df6b6000,400+df6b6400,400 df6b6000,800+df6b6800,400 df6b6000,c00+df6b6c00,400 df6b6000,1000+df6b5000,400 (df6b6000, 1000)
df6b5000,400+df6b5400,400 df6b5000,800+df6b5800,400 df6b5000,c00+df6b5c00,400 df6b5000,1000+df6b4000,400 (df6b5000, 1000)
df6b4000,400+df6b4400,400 df6b4000,800+df6b4800,400 df6b4000,c00+df6b4c00,400 df6b4000,1000+df6b3000,400 (df6b4000, 1000)
df6b3000,400+df6b3400,400 df6b3000,800+df6b3800,400 df6b3000,c00+df6b3c00,400 df6b3000,1000+df6b2000,400 (df6b3000, 1000)
df6b2000,400+df6b2400,400 df6b2000,800+df6b2800,400 df6b2000,c00+df6b2c00,400 df6b2000,1000+df6b1000,400 (df6b2000, 1000)
df6b1000,400+df6b1400,400 df6b1000,800+df6b1800,400 df6b1000,c00+df6b1c00,400 df6b1000,1000+df6af000,400 (df6b1000, 1000)
df6af000,400+df6af400,400 df6af000,800+df6af800,400 df6af000,c00+df6afc00,400 df6af000,1000+df6ae000,400 (df6af000, 1000)
df6ae000,400+df6ae400,400 df6ae000,800+df6ae800,400 df6ae000,c00+df6aec00,400 df6ae000,1000+df6ad000,400 (df6ae000, 1000)
df6ad000,400+df6ad400,400 df6ad000,800+df6ad800,400 df6ad000,c00+df6adc00,400 df6ad000,1000+df6ac000,400 (df6ad000, 1000)
df6ac000,400+df6ac400,400 df6ac000,800+df6ac800,400 df6ac000,c00+df6acc00,400 df6ac000,1000+df6ab000,400 (df6ac000, 1000)
df6ab000,400+df6ab400,400 df6ab000,800+df6ab800,400 df6ab000,c00+df6abc00,400 (0xdf6ab000,1000)
() DONE 17 mappings
() START 64 entries, dfd7a800,400
() DONE (nents 47)
() START 64 entries
df69a000,400+df69a400,400 df69a000,800+df69a800,400 df69a000,c00+df69ac00,400 df69a000,1000+df699000,400 (df69a000, 1000)
df699000,400+df699400,400 df699000,800+df699800,400 df699000,c00+df699c00,400 df699000,1000+df698000,400 (df699000, 1000)
df698000,400+df698400,400 df698000,800+df698800,400 df698000,c00+df698c00,400 df698000,1000+df697000,400 (df698000, 1000)
df697000,400+df697400,400 df697000,800+df697800,400 df697000,c00+df697c00,400 df697000,1000+df696000,400 (df697000, 1000)
df696000,400+df696400,400 df696000,800+df696800,400 df696000,c00+df696c00,400 df696000,1000+df694000,400 (df696000, 1000)
df694000,400+df694400,400 df694000,800+df694800,400 df694000,c00+df694c00,400 df694000,1000+df693000,400 (df694000, 1000)
df693000,400+df693400,400 df693000,800+df693800,400 df693000,c00+df693c00,400 df693000,1000+df692000,400 (df693000, 1000)
df692000,400+df692400,400 df692000,800+df692800,400 df692000,c00+df692c00,400 df692000,1000+df691000,400 (df692000, 1000)
df691000,400+df691400,400 df691000,800+df691800,400 df691000,c00+df691c00,400 df691000,1000+df690000,400 (df691000, 1000)
df690000,400+df690400,400 df690000,800+df690800,400 df690000,c00+df690c00,400 df690000,1000+df68f000,400 (df690000, 1000)
df68f000,400+df68f400,400 df68f000,800+df68f800,400 df68f000,c00+df68fc00,400 df68f000,1000+df68e000,400 (df68f000, 1000)
df68e000,400+df68e400,400 df68e000,800+df68e800,400 df68e000,c00+df68ec00,400 df68e000,1000+df68d000,400 (df68e000, 1000)
df68d000,400+df68d400,400 df68d000,800+df68d800,400 df68d000,c00+df68dc00,400 df68d000,1000+df68c000,400 (df68d000, 1000)
df68c000,400+df68c400,400 df68c000,800+df68c800,400 df68c000,c00+df68cc00,400 df68c000,1000+df68b000,400 (df68c000, 1000)
df68b000,400+df68b400,400 df68b000,800+df68b800,400 df68b000,c00+df68bc00,400 df68b000,1000+df689000,400 (df68b000, 1000)
df689000,400+df689400,400 df689000,800+df689800,400 df689000,c00+df689c00,400 (0xdf689000,1000)
() DONE 16 mappings
() START 64 entries, df69a000,400
() DONE (nents 48)
() START 64 entries
df688000,400+df688400,400 df688000,800+df688800,400 df688000,c00+df688c00,400 df688000,1000+df687000,400 (df688000, 1000)
df687000,400+df687400,400 df687000,800+df687800,400 df687000,c00+df687c00,400 df687000,1000+df686000,400 (df687000, 1000)
df686000,400+df686400,400 df686000,800+df686800,400 df686000,c00+df686c00,400 df686000,1000+df685000,400 (df686000, 1000)
df685000,400+df685400,400 df685000,800+df685800,400 df685000,c00+df685c00,400 df685000,1000+df684000,400 (df685000, 1000)
df684000,400+df684400,400 df684000,800+df684800,400 df684000,c00+df684c00,400 df684000,1000+df683000,400 (df684000, 1000)
df683000,400+df683400,400 df683000,800+df683800,400 df683000,c00+df683c00,400 df683000,1000+df682000,400 (df683000, 1000)
df682000,400+df682400,400 df682000,800+df682800,400 df682000,c00+df682c00,400 df682000,1000+df681000,400 (df682000, 1000)
df681000,400+df681400,400 df681000,800+df681800,400 df681000,c00+df681c00,400 df681000,1000+df680000,400 (df681000, 1000)
df680000,400+df680400,400 df680000,800+df680800,400 df680000,c00+df680c00,400 df680000,1000+df67e000,400 (df680000, 1000)
df67e000,400+df67e400,400 df67e000,800+df67e800,400 df67e000,c00+df67ec00,400 df67e000,1000+df67d000,400 (df67e000, 1000)
df67d000,400+df67d400,400 df67d000,800+df67d800,400 df67d000,c00+df67dc00,400 df67d000,1000+df67c000,400 (df67d000, 1000)
df67c000,400+df67c400,400 df67c000,800+df67c800,400 df67c000,c00+df67cc00,400 df67c000,1000+df67b000,400 (df67c000, 1000)
df67b000,400+df67b400,400 df67b000,800+df67b800,400 df67b000,c00+df67bc00,400 df67b000,1000+df67a000,400 (df67b000, 1000)
df67a000,400+df67a400,400 df67a000,800+df67a800,400 df67a000,c00+df67ac00,400 df67a000,1000+df679000,400 (df67a000, 1000)
df679000,400+df679400,400 df679000,800+df679800,400 df679000,c00+df679c00,400 df679000,1000+df678000,400 (df679000, 1000)
df678000,400+df678400,400 df678000,800+df678800,400 df678000,c00+df678c00,400 (0xdf678000,1000)
() DONE 16 mappings
() START 64 entries, df688000,400
() DONE (nents 48)
() START 64 entries
df675000,400+df675400,400 df675000,800+df675800,400 df675000,c00+df675c00,400 df675000,1000+df674000,400 (df675000, 1000)
df674000,400+df674400,400 df674000,800+df674800,400 df674000,c00+df674c00,400 df674000,1000+df673000,400 (df674000, 1000)
df673000,400+df673400,400 df673000,800+df673800,400 df673000,c00+df673c00,400 df673000,1000+df671000,400 (df673000, 1000)
df671000,400+df671400,400 df671000,800+df671800,400 df671000,c00+df671c00,400 df671000,1000+df670000,400 (df671000, 1000)
df670000,400+df670400,400 df670000,800+df670800,400 df670000,c00+df670c00,400 df670000,1000+df66f000,400 (df670000, 1000)
df66f000,400+df66f400,400 df66f000,800+df66f800,400 df66f000,c00+df66fc00,400 df66f000,1000+df66e000,400 (df66f000, 1000)
df66e000,400+df66e400,400 df66e000,800+df66e800,400 df66e000,c00+df66ec00,400 df66e000,1000+df66d000,400 (df66e000, 1000)
df66d000,400+df66d400,400 df66d000,800+df66d800,400 df66d000,c00+df66dc00,400 df66d000,1000+df66c000,400 (df66d000, 1000)
df66c000,400+df66c400,400 df66c000,800+df66c800,400 df66c000,c00+df66cc00,400 df66c000,1000+df66b000,400 (df66c000, 1000)
df66b000,400+df66b400,400 df66b000,800+df66b800,400 df66b000,c00+df66bc00,400 df66b000,1000+df66a000,400 (df66b000, 1000)
df66a000,400+df66a400,400 df66a000,800+df66a800,400 df66a000,c00+df66ac00,400 df66a000,1000+df669000,400 (df66a000, 1000)
df669000,400+df669400,400 df669000,800+df669800,400 df669000,c00+df669c00,400 df669000,1000+df668000,400 (df669000, 1000)
df668000,400+df668400,400 df668000,800+df668800,400 df668000,c00+df668c00,400 df668000,1000+df666000,400 (df668000, 1000)
df666000,400+df666400,400 df666000,800+df666800,400 df666000,c00+df666c00,400 df666000,1000+df665000,400 (df666000, 1000)
df665000,400+df665400,400 df665000,800+df665800,400 df665000,c00+df665c00,400 df665000,1000+df664000,400 (df665000, 1000)
df664000,400+df664400,400 df664000,800+df664800,400 df664000,c00+df664c00,400 (0xdf664000,1000)
() DONE 16 mappings
() START 64 entries, df675000,400
() DONE (nents 48)
() START 64 entries
df663000,400+df663400,400 df663000,800+df663800,400 df663000,c00+df663c00,400 df663000,1000+df662000,400 (df663000, 1000)
df662000,400+df662400,400 df662000,800+df662800,400 df662000,c00+df662c00,400 df662000,1000+df661000,400 (df662000, 1000)
df661000,400+df661400,400 df661000,800+df661800,400 df661000,c00+df661c00,400 df661000,1000+df660000,400 (df661000, 1000)
df660000,400+df660400,400 df660000,800+df660800,400 df660000,c00+df660c00,400 df660000,1000+df65f000,400 (df660000, 1000)
df65f000,400+df65f400,400 df65f000,800+df65f800,400 df65f000,c00+df65fc00,400 df65f000,1000+df65e000,400 (df65f000, 1000)
df65e000,400+df65e400,400 df65e000,800+df65e800,400 df65e000,c00+df65ec00,400 df65e000,1000+df65d000,400 (df65e000, 1000)
df65d000,400+df65d400,400 df65d000,800+df65d800,400 df65d000,c00+df65dc00,400 df65d000,1000+df65b000,400 (df65d000, 1000)
df65b000,400+df65b400,400 df65b000,800+df65b800,400 df65b000,c00+df65bc00,400 df65b000,1000+df65a000,400 (df65b000, 1000)
df65a000,400+df65a400,400 df65a000,800+df65a800,400 df65a000,c00+df65ac00,400 df65a000,1000+df659000,400 (df65a000, 1000)
df659000,400+df659400,400 df659000,800+df659800,400 df659000,c00+df659c00,400 df659000,1000+df658000,400 (df659000, 1000)
df658000,400+df658400,400 df658000,800+df658800,400 df658000,c00+df658c00,400 df658000,1000+df657000,400 (df658000, 1000)
df657000,400+df657400,400 df657000,800+df657800,400 df657000,c00+df657c00,400 df657000,1000+df656000,400 (df657000, 1000)
df656000,400+df656400,400 df656000,800+df656800,400 df656000,c00+df656c00,400 df656000,1000+df655000,400 (df656000, 1000)
df655000,400+df655400,400 df655000,800+df655800,400 df655000,c00+df655c00,400 df655000,1000+df654000,400 (df655000, 1000)
df654000,400+df654400,400 df654000,800+df654800,400 df654000,c00+df654c00,400 df654000,1000+df653000,400 (df654000, 1000)
df653000,400+df653400,400 df653000,800+df653800,400 df653000,c00+df653c00,400 (0xdf653000,1000)
() DONE 16 mappings
() START 64 entries, df663000,400
() DONE (nents 48)
5+0 records in
5+0 records out
gggC3000:~#