From: david-sarah Date: Fri, 10 Sep 2010 19:54:22 +0000 (-0700) Subject: docs/frontends/FTP-and-SFTP.txt: docs/performance.txt, architecture.txt: updates... X-Git-Tag: allmydata-tahoe-1.8.0c4~7 X-Git-Url: https://git.rkrishnan.org/specifications/components?a=commitdiff_plain;h=f32dddbcedea3c7c1bb82287b28141884257e477;p=tahoe-lafs%2Ftahoe-lafs.git docs/frontends/FTP-and-SFTP.txt: docs/performance.txt, architecture.txt: updates taking into account new downloader (revised). refs #798 --- diff --git a/docs/architecture.txt b/docs/architecture.txt index 0451d4e9..604b5947 100644 --- a/docs/architecture.txt +++ b/docs/architecture.txt @@ -231,9 +231,12 @@ sense to set servers_of_happiness = N. When downloading a file, the current version just asks all known servers for any shares they might have. Once it has received enough responses that it -knows where to find the needed k shares, it downloads the shares from those -servers. (This means that it tends to download shares from the fastest -servers.) +knows where to find the needed k shares, it downloads at least the first +segment from those servers. This means that it tends to download shares from +the fastest servers. If some servers had more than one share, it will continue +sending "Do You Have Block" requests to other servers, so that it can download +subsequent segments from distinct servers (sorted by their DYHB round-trip +times), if possible. *future work* diff --git a/docs/performance.txt b/docs/performance.txt index 45d63cad..83d7a7a7 100644 --- a/docs/performance.txt +++ b/docs/performance.txt @@ -40,25 +40,16 @@ notes: Tahoe-LAFS generates a new RSA keypair for each mutable file that == Downloading B bytes of an A-byte immutable file == -network: A +network: B memory footprint: 128KiB -notes: When asked to read an arbitrary range of an immutable file, - Tahoe-LAFS will download from the beginning of the file up until - it has enough of the file to satisfy the requested read. - Depending on where in the file the requested range is, this can - mean that the entire file is downloaded before the request is - satisfied. Tahoe-LAFS will continue to download the rest of the - file even after the request is satisfied, so in any case where the - file actually has to downloaded from the grid, reading part of an - immutable file will result in downloading all of the immutable - file. Ticket #798 is a proposal to change this behavior. - - Tahoe-LAFS will cache files that are read in this manner for a - short while, so subsequent reads of the same file may be served - entirely from cache, depending on what part of the file they need - to read, what part of the file was read by previous reads, and - how much time has elapsed since the last read. +notes: When Tahoe-LAFS 1.8.0 or later is asked to read an arbitrary range + of an immutable file, only the 128-KiB segments that overlap the + requested range will be downloaded. + + (Earlier versions would download from the beginning of the file up + until the end of the requested range, and then continue to download + the rest of the file even after the request was satisfied.) == Downloading B bytes of an A-byte mutable file ==