If we modify bufferlist::c_str() to bufferlist::c_str(bool align). If (align) Posix_memalign(data, CEPH_PAGE_SIZE, len) Else Origin code. I think this is simple and correctly code. Jianpeng Thanks! > -----Original Message----- > From: ceph-devel-owner@xxxxxxxxxxxxxxx > [mailto:ceph-devel-owner@xxxxxxxxxxxxxxx] On Behalf Of Loic Dachary > Sent: Tuesday, September 16, 2014 1:20 AM > To: Janne Grunau; ceph-devel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 2/3] ec: make use of added aligned buffers > > Hi Janne, > > See below: > > On 15/09/2014 17:55, Janne Grunau wrote: > > Requiring page aligned buffers and realigning the input if necessary > > creates measurable oberhead. ceph_erasure_code_benchmark is ~30% > > faster with this change for technique=reed_sol_van,k=2,m=1. > > > > Also prevents a misaligned buffer when bufferlist::c_str(bufferlist) > > has to allocate a new buffer to provide continuous one. See bug #9408 > > > > Signed-off-by: Janne Grunau <j@xxxxxxxxxx> > > --- > > src/erasure-code/ErasureCode.cc | 46 > > +++++++++++++++++++++++++---------------- > > src/erasure-code/ErasureCode.h | 3 ++- > > 2 files changed, 30 insertions(+), 19 deletions(-) > > > > diff --git a/src/erasure-code/ErasureCode.cc > > b/src/erasure-code/ErasureCode.cc index 5953f49..078f60b 100644 > > --- a/src/erasure-code/ErasureCode.cc > > +++ b/src/erasure-code/ErasureCode.cc > > @@ -54,22 +54,38 @@ int > ErasureCode::minimum_to_decode_with_cost(const > > set<int> &want_to_read, } > > > > int ErasureCode::encode_prepare(const bufferlist &raw, > > - bufferlist *prepared) const > > + map<int, bufferlist> &encoded) > const > > { > > unsigned int k = get_data_chunk_count(); > > unsigned int m = get_chunk_count() - k; > > unsigned blocksize = get_chunk_size(raw.length()); > > - unsigned padded_length = blocksize * k; > > - *prepared = raw; > > - if (padded_length - raw.length() > 0) { > > - bufferptr pad(padded_length - raw.length()); > > - pad.zero(); > > - prepared->push_back(pad); > > + unsigned pad_len = blocksize * k - raw.length(); > > + > > + bufferlist prepared = raw; > > + > > + if (!prepared.is_aligned()) { > > + prepared.rebuild_aligned(); > > + } > > + > > + for (unsigned int i = 0; i < k - !!pad_len; i++) { > > + int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[i] : i; > > + bufferlist &chunk = encoded[chunk_index]; > > + chunk.substr_of(prepared, i * blocksize, blocksize); } > > It is possible for more than one chunk to be padding. It's a border case but... for > instance with alignment = 16, k=12 and in of length 1550 you end up with two > padding chunks because the blocksize is 144. > > > + if (pad_len > 0) { > > + int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[k - 1] : k - > 1; > > + bufferlist &chunk = encoded[chunk_index]; > > + bufferptr padded(buffer::create_aligned(blocksize)); > > + raw.copy((k - 1) * blocksize, blocksize - pad_len, padded.c_str()); > > + padded.zero(blocksize - pad_len, pad_len); > > + chunk.push_back(padded); > > } > > - unsigned coding_length = blocksize * m; > > - bufferptr coding(buffer::create_page_aligned(coding_length)); > > - prepared->push_back(coding); > > - prepared->rebuild_page_aligned(); > > + for (unsigned int i = k; i < k + m; i++) { > > + int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[i] : i; > > + bufferlist &chunk = encoded[chunk_index]; > > + chunk.push_back(buffer::create_aligned(blocksize)); > > + } > > + > > return 0; > > } > > > > @@ -80,15 +96,9 @@ int ErasureCode::encode(const set<int> > &want_to_encode, > > unsigned int k = get_data_chunk_count(); > > unsigned int m = get_chunk_count() - k; > > bufferlist out; > > - int err = encode_prepare(in, &out); > > + int err = encode_prepare(in, *encoded); > > if (err) > > return err; > > - unsigned blocksize = get_chunk_size(in.length()); > > - for (unsigned int i = 0; i < k + m; i++) { > > - int chunk_index = chunk_mapping.size() > 0 ? chunk_mapping[i] : i; > > - bufferlist &chunk = (*encoded)[chunk_index]; > > - chunk.substr_of(out, i * blocksize, blocksize); > > - } > > encode_chunks(want_to_encode, encoded); > > for (unsigned int i = 0; i < k + m; i++) { > > if (want_to_encode.count(i) == 0) diff --git > > a/src/erasure-code/ErasureCode.h b/src/erasure-code/ErasureCode.h > > index 7aaea95..62aa383 100644 > > --- a/src/erasure-code/ErasureCode.h > > +++ b/src/erasure-code/ErasureCode.h > > @@ -46,7 +46,8 @@ namespace ceph { > > const map<int, int> > &available, > > set<int> *minimum); > > > > - int encode_prepare(const bufferlist &raw, bufferlist *prepared) const; > > + int encode_prepare(const bufferlist &raw, > > + map<int, bufferlist> &encoded) const; > > > > virtual int encode(const set<int> &want_to_encode, > > const bufferlist &in, > > > > -- > Loïc Dachary, Artisan Logiciel Libre -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
