iostat: what is exactly the concept of merge
Clash Royale CLAN TAG#URR8PPP
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From iostat man pages:
rrqm/s
The number of read requests merged per second that were queued to the device.
wrqm/s
The number of write requests merged per second that were queued to the device.
r/s
The number (after merges) of read requests completed per second for the device.
w/s
The number (after merges) of write requests completed per second for the device.
Can anyone elaborate on the merge concept since the documentation does not provide any further details?
io iostat
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
asked Aug 15 at 9:03
pkaramol
338112
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up vote
1
down vote
favorite
From iostat man pages:
rrqm/s
The number of read requests merged per second that were queued to the device.
wrqm/s
The number of write requests merged per second that were queued to the device.
r/s
The number (after merges) of read requests completed per second for the device.
w/s
The number (after merges) of write requests completed per second for the device.
Can anyone elaborate on the merge concept since the documentation does not provide any further details?
io iostat
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
asked Aug 15 at 9:03
pkaramol
338112
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
From iostat man pages:
rrqm/s
The number of read requests merged per second that were queued to the device.
wrqm/s
The number of write requests merged per second that were queued to the device.
r/s
The number (after merges) of read requests completed per second for the device.
w/s
The number (after merges) of write requests completed per second for the device.
Can anyone elaborate on the merge concept since the documentation does not provide any further details?
io iostat
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
asked Aug 15 at 9:03
pkaramol
338112
From iostat man pages:
rrqm/s
The number of read requests merged per second that were queued to the device.
wrqm/s
The number of write requests merged per second that were queued to the device.
r/s
The number (after merges) of read requests completed per second for the device.
w/s
The number (after merges) of write requests completed per second for the device.
Can anyone elaborate on the merge concept since the documentation does not provide any further details?
io iostat
io iostat
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
asked Aug 15 at 9:03
pkaramol
338112
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
asked Aug 15 at 9:03
pkaramol
338112
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
edited Aug 15 at 9:43
Rui F Ribeiro
36.6k1271116
36.6k1271116
asked Aug 15 at 9:03
pkaramol
338112
asked Aug 15 at 9:03
pkaramol
338112
asked Aug 15 at 9:03
pkaramol
338112
338112
add a comment |Â
add a comment |Â
1 Answer
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oldest
votes
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2
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A merge happens when two i/o requests can be collapsed into one single longer-length request. For example, a write to block 1234 followed by a write to block 1235 can be merged into a single i/o request for block 1234 of length 2 blocks. As this sort of situation can be fairly common it is worth putting the effort in the kernel to do the merge, freeing up an i/o request structture, and reducing interrupt overhead.
If you are interested in more detailed statistics on this aspect of i/o see the pdf btt user guide which is part of blktrace.
answered Aug 15 at 12:10
meuh
30k11752
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
accepted
A merge happens when two i/o requests can be collapsed into one single longer-length request. For example, a write to block 1234 followed by a write to block 1235 can be merged into a single i/o request for block 1234 of length 2 blocks. As this sort of situation can be fairly common it is worth putting the effort in the kernel to do the merge, freeing up an i/o request structture, and reducing interrupt overhead.
If you are interested in more detailed statistics on this aspect of i/o see the pdf btt user guide which is part of blktrace.
answered Aug 15 at 12:10
meuh
30k11752
add a comment |Â
up vote
2
down vote
accepted
A merge happens when two i/o requests can be collapsed into one single longer-length request. For example, a write to block 1234 followed by a write to block 1235 can be merged into a single i/o request for block 1234 of length 2 blocks. As this sort of situation can be fairly common it is worth putting the effort in the kernel to do the merge, freeing up an i/o request structture, and reducing interrupt overhead.
If you are interested in more detailed statistics on this aspect of i/o see the pdf btt user guide which is part of blktrace.
answered Aug 15 at 12:10
meuh
30k11752
add a comment |Â
up vote
2
down vote
accepted
up vote
2
down vote
accepted
A merge happens when two i/o requests can be collapsed into one single longer-length request. For example, a write to block 1234 followed by a write to block 1235 can be merged into a single i/o request for block 1234 of length 2 blocks. As this sort of situation can be fairly common it is worth putting the effort in the kernel to do the merge, freeing up an i/o request structture, and reducing interrupt overhead.
If you are interested in more detailed statistics on this aspect of i/o see the pdf btt user guide which is part of blktrace.
answered Aug 15 at 12:10
meuh
30k11752
A merge happens when two i/o requests can be collapsed into one single longer-length request. For example, a write to block 1234 followed by a write to block 1235 can be merged into a single i/o request for block 1234 of length 2 blocks. As this sort of situation can be fairly common it is worth putting the effort in the kernel to do the merge, freeing up an i/o request structture, and reducing interrupt overhead.
If you are interested in more detailed statistics on this aspect of i/o see the pdf btt user guide which is part of blktrace.
answered Aug 15 at 12:10
meuh
30k11752
edited Aug 15 at 12:16
answered Aug 15 at 12:10
meuh
30k11752
answered Aug 15 at 12:10
meuh
30k11752
answered Aug 15 at 12:10
meuh
30k11752
30k11752
add a comment |Â
add a comment |Â
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